org.apache.hadoop.hdfs.DFSConfigKeys.java Source code

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hdfs;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
import org.apache.hadoop.hdfs.net.DFSNetworkTopology;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.hdfs.protocol.HdfsConstants.StoragePolicySatisfierMode;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyRackFaultTolerant;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.RamDiskReplicaLruTracker;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.ReservedSpaceCalculator;
import org.apache.hadoop.hdfs.web.URLConnectionFactory;
import org.apache.hadoop.http.HttpConfig;

/** 
 * This class contains constants for configuration keys and default values
 * used in hdfs.
 */
@InterfaceAudience.Private
public class DFSConfigKeys extends CommonConfigurationKeys {
    public static final String DFS_BLOCK_SIZE_KEY = HdfsClientConfigKeys.DFS_BLOCK_SIZE_KEY;
    public static final long DFS_BLOCK_SIZE_DEFAULT = HdfsClientConfigKeys.DFS_BLOCK_SIZE_DEFAULT;
    public static final String DFS_REPLICATION_KEY = HdfsClientConfigKeys.DFS_REPLICATION_KEY;
    public static final short DFS_REPLICATION_DEFAULT = HdfsClientConfigKeys.DFS_REPLICATION_DEFAULT;

    public static final String DFS_STREAM_BUFFER_SIZE_KEY = "dfs.stream-buffer-size";
    public static final int DFS_STREAM_BUFFER_SIZE_DEFAULT = 4096;
    public static final String DFS_BYTES_PER_CHECKSUM_KEY = HdfsClientConfigKeys.DFS_BYTES_PER_CHECKSUM_KEY;
    public static final int DFS_BYTES_PER_CHECKSUM_DEFAULT = HdfsClientConfigKeys.DFS_BYTES_PER_CHECKSUM_DEFAULT;
    @Deprecated
    public static final String DFS_USER_HOME_DIR_PREFIX_KEY = HdfsClientConfigKeys.DFS_USER_HOME_DIR_PREFIX_KEY;
    @Deprecated
    public static final String DFS_USER_HOME_DIR_PREFIX_DEFAULT = HdfsClientConfigKeys.DFS_USER_HOME_DIR_PREFIX_DEFAULT;
    public static final String DFS_CHECKSUM_TYPE_KEY = HdfsClientConfigKeys.DFS_CHECKSUM_TYPE_KEY;
    public static final String DFS_CHECKSUM_TYPE_DEFAULT = HdfsClientConfigKeys.DFS_CHECKSUM_TYPE_DEFAULT;
    public static final String DFS_WEBHDFS_ACL_PERMISSION_PATTERN_DEFAULT = HdfsClientConfigKeys.DFS_WEBHDFS_ACL_PERMISSION_PATTERN_DEFAULT;
    public static final String DFS_WEBHDFS_NETTY_LOW_WATERMARK = "dfs.webhdfs.netty.low.watermark";
    public static final int DFS_WEBHDFS_NETTY_LOW_WATERMARK_DEFAULT = 32768;
    public static final String DFS_WEBHDFS_NETTY_HIGH_WATERMARK = "dfs.webhdfs.netty.high.watermark";
    public static final int DFS_WEBHDFS_NETTY_HIGH_WATERMARK_DEFAULT = 65535;
    public static final String DFS_WEBHDFS_UGI_EXPIRE_AFTER_ACCESS_KEY = "dfs.webhdfs.ugi.expire.after.access";
    public static final int DFS_WEBHDFS_UGI_EXPIRE_AFTER_ACCESS_DEFAULT = 10 * 60 * 1000; //10 minutes
    public static final String DFS_WEBHDFS_USE_IPC_CALLQ = "dfs.webhdfs.use.ipc.callq";
    public static final boolean DFS_WEBHDFS_USE_IPC_CALLQ_DEFAULT = true;

    // HA related configuration
    public static final String DFS_DATANODE_RESTART_REPLICA_EXPIRY_KEY = "dfs.datanode.restart.replica.expiration";
    public static final long DFS_DATANODE_RESTART_REPLICA_EXPIRY_DEFAULT = 50;
    public static final String DFS_NAMENODE_BACKUP_ADDRESS_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_BACKUP_ADDRESS_KEY;
    public static final String DFS_NAMENODE_BACKUP_ADDRESS_DEFAULT = "localhost:50100";
    public static final String DFS_NAMENODE_BACKUP_HTTP_ADDRESS_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_BACKUP_HTTP_ADDRESS_KEY;
    public static final String DFS_NAMENODE_BACKUP_HTTP_ADDRESS_DEFAULT = "0.0.0.0:50105";
    public static final String DFS_NAMENODE_BACKUP_SERVICE_RPC_ADDRESS_KEY = "dfs.namenode.backup.dnrpc-address";
    public static final String DFS_PROVIDED_ALIASMAP_INMEMORY_RPC_ADDRESS = HdfsClientConfigKeys.DFS_PROVIDED_ALIASMAP_INMEMORY_RPC_ADDRESS;
    public static final String DFS_PROVIDED_ALIASMAP_INMEMORY_RPC_ADDRESS_DEFAULT = "0.0.0.0:50200";
    public static final String DFS_PROVIDED_ALIASMAP_INMEMORY_RPC_BIND_HOST = "dfs.provided.aliasmap.inmemory.rpc.bind-host";

    public static final String DFS_PROVIDED_ALIASMAP_INMEMORY_LEVELDB_DIR = "dfs.provided.aliasmap.inmemory.leveldb.dir";
    public static final String DFS_PROVIDED_ALIASMAP_INMEMORY_BATCH_SIZE = "dfs.provided.aliasmap.inmemory.batch-size";
    public static final int DFS_PROVIDED_ALIASMAP_INMEMORY_BATCH_SIZE_DEFAULT = 500;
    public static final String DFS_PROVIDED_ALIASMAP_INMEMORY_ENABLED = "dfs.provided.aliasmap.inmemory.enabled";
    public static final boolean DFS_PROVIDED_ALIASMAP_INMEMORY_ENABLED_DEFAULT = false;
    public static final String DFS_PROVIDED_ALIASMAP_INMEMORY_SERVER_LOG = "dfs.provided.aliasmap.inmemory.server.log";
    public static final boolean DFS_PROVIDED_ALIASMAP_INMEMORY_SERVER_LOG_DEFAULT = false;

    public static final String DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_KEY;
    public static final long DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_DEFAULT = 10 * 1024 * 1024;
    public static final String DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_KEY = "dfs.datanode.balance.max.concurrent.moves";
    public static final int DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_DEFAULT = 50;
    @Deprecated
    public static final String DFS_DATANODE_READAHEAD_BYTES_KEY = HdfsClientConfigKeys.DFS_DATANODE_READAHEAD_BYTES_KEY;
    @Deprecated
    public static final long DFS_DATANODE_READAHEAD_BYTES_DEFAULT = HdfsClientConfigKeys.DFS_DATANODE_READAHEAD_BYTES_DEFAULT;
    public static final String DFS_DATANODE_DROP_CACHE_BEHIND_WRITES_KEY = "dfs.datanode.drop.cache.behind.writes";
    public static final boolean DFS_DATANODE_DROP_CACHE_BEHIND_WRITES_DEFAULT = false;
    public static final String DFS_DATANODE_SYNC_BEHIND_WRITES_KEY = "dfs.datanode.sync.behind.writes";
    public static final boolean DFS_DATANODE_SYNC_BEHIND_WRITES_DEFAULT = false;
    public static final String DFS_DATANODE_SYNC_BEHIND_WRITES_IN_BACKGROUND_KEY = "dfs.datanode.sync.behind.writes.in.background";
    public static final boolean DFS_DATANODE_SYNC_BEHIND_WRITES_IN_BACKGROUND_DEFAULT = false;
    public static final String DFS_DATANODE_DROP_CACHE_BEHIND_READS_KEY = "dfs.datanode.drop.cache.behind.reads";
    public static final boolean DFS_DATANODE_DROP_CACHE_BEHIND_READS_DEFAULT = false;
    public static final String DFS_DATANODE_USE_DN_HOSTNAME = "dfs.datanode.use.datanode.hostname";
    public static final boolean DFS_DATANODE_USE_DN_HOSTNAME_DEFAULT = false;
    public static final String DFS_DATANODE_MAX_LOCKED_MEMORY_KEY = "dfs.datanode.max.locked.memory";
    public static final long DFS_DATANODE_MAX_LOCKED_MEMORY_DEFAULT = 0;
    public static final String DFS_DATANODE_FSDATASETCACHE_MAX_THREADS_PER_VOLUME_KEY = "dfs.datanode.fsdatasetcache.max.threads.per.volume";
    public static final int DFS_DATANODE_FSDATASETCACHE_MAX_THREADS_PER_VOLUME_DEFAULT = 4;
    public static final String DFS_DATANODE_LAZY_WRITER_INTERVAL_SEC = "dfs.datanode.lazywriter.interval.sec";
    public static final int DFS_DATANODE_LAZY_WRITER_INTERVAL_DEFAULT_SEC = 60;
    public static final String DFS_DATANODE_RAM_DISK_REPLICA_TRACKER_KEY = "dfs.datanode.ram.disk.replica.tracker";
    public static final Class<RamDiskReplicaLruTracker> DFS_DATANODE_RAM_DISK_REPLICA_TRACKER_DEFAULT = RamDiskReplicaLruTracker.class;
    public static final String DFS_DATANODE_NETWORK_COUNTS_CACHE_MAX_SIZE_KEY = "dfs.datanode.network.counts.cache.max.size";
    public static final int DFS_DATANODE_NETWORK_COUNTS_CACHE_MAX_SIZE_DEFAULT = Integer.MAX_VALUE;
    public static final String DFS_DATANODE_NON_LOCAL_LAZY_PERSIST = "dfs.datanode.non.local.lazy.persist";
    public static final boolean DFS_DATANODE_NON_LOCAL_LAZY_PERSIST_DEFAULT = false;

    // This setting is for testing/internal use only.
    public static final String DFS_DATANODE_DUPLICATE_REPLICA_DELETION = "dfs.datanode.duplicate.replica.deletion";
    public static final boolean DFS_DATANODE_DUPLICATE_REPLICA_DELETION_DEFAULT = true;

    public static final String DFS_DN_CACHED_DFSUSED_CHECK_INTERVAL_MS = "dfs.datanode.cached-dfsused.check.interval.ms";
    public static final long DFS_DN_CACHED_DFSUSED_CHECK_INTERVAL_DEFAULT_MS = 600000;

    public static final String DFS_NAMENODE_PATH_BASED_CACHE_BLOCK_MAP_ALLOCATION_PERCENT = "dfs.namenode.path.based.cache.block.map.allocation.percent";
    public static final float DFS_NAMENODE_PATH_BASED_CACHE_BLOCK_MAP_ALLOCATION_PERCENT_DEFAULT = 0.25f;

    public static final int DFS_NAMENODE_HTTP_PORT_DEFAULT = HdfsClientConfigKeys.DFS_NAMENODE_HTTP_PORT_DEFAULT;
    public static final String DFS_NAMENODE_HTTP_ADDRESS_KEY = HdfsClientConfigKeys.DFS_NAMENODE_HTTP_ADDRESS_KEY;
    public static final String DFS_NAMENODE_HTTP_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_NAMENODE_HTTP_PORT_DEFAULT;
    public static final String DFS_NAMENODE_HTTP_BIND_HOST_KEY = "dfs.namenode.http-bind-host";
    public static final String DFS_NAMENODE_RPC_ADDRESS_KEY = HdfsClientConfigKeys.DFS_NAMENODE_RPC_ADDRESS_KEY;
    public static final String DFS_NAMENODE_RPC_BIND_HOST_KEY = "dfs.namenode.rpc-bind-host";
    public static final String DFS_NAMENODE_SERVICE_RPC_ADDRESS_KEY = "dfs.namenode.servicerpc-address";
    public static final String DFS_NAMENODE_SERVICE_RPC_BIND_HOST_KEY = "dfs.namenode.servicerpc-bind-host";
    public static final String DFS_NAMENODE_LIFELINE_RPC_ADDRESS_KEY = "dfs.namenode.lifeline.rpc-address";
    public static final String DFS_NAMENODE_LIFELINE_RPC_BIND_HOST_KEY = "dfs.namenode.lifeline.rpc-bind-host";
    public static final String DFS_NAMENODE_MAX_OBJECTS_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_MAX_OBJECTS_KEY;
    public static final long DFS_NAMENODE_MAX_OBJECTS_DEFAULT = 0;
    public static final String DFS_NAMENODE_SAFEMODE_EXTENSION_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_SAFEMODE_EXTENSION_KEY;
    public static final int DFS_NAMENODE_SAFEMODE_EXTENSION_DEFAULT = 30000;
    public static final String DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_KEY;
    public static final float DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_DEFAULT = 0.999f;
    // set this to a slightly smaller value than
    // DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_DEFAULT to populate
    // needed replication queues before exiting safe mode
    public static final String DFS_NAMENODE_REPL_QUEUE_THRESHOLD_PCT_KEY = "dfs.namenode.replqueue.threshold-pct";
    public static final String DFS_NAMENODE_SAFEMODE_MIN_DATANODES_KEY = "dfs.namenode.safemode.min.datanodes";
    public static final int DFS_NAMENODE_SAFEMODE_MIN_DATANODES_DEFAULT = 0;
    public static final String DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY;
    public static final String DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_DEFAULT = "0.0.0.0:9868";
    public static final String DFS_NAMENODE_SECONDARY_HTTPS_ADDRESS_KEY = "dfs.namenode.secondary.https-address";
    public static final String DFS_NAMENODE_SECONDARY_HTTPS_ADDRESS_DEFAULT = "0.0.0.0:9869";
    public static final String DFS_NAMENODE_CHECKPOINT_QUIET_MULTIPLIER_KEY = "dfs.namenode.checkpoint.check.quiet-multiplier";
    public static final double DFS_NAMENODE_CHECKPOINT_QUIET_MULTIPLIER_DEFAULT = 1.5;
    public static final String DFS_NAMENODE_CHECKPOINT_CHECK_PERIOD_KEY = "dfs.namenode.checkpoint.check.period";
    public static final long DFS_NAMENODE_CHECKPOINT_CHECK_PERIOD_DEFAULT = 60;
    public static final String DFS_NAMENODE_CHECKPOINT_PERIOD_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_CHECKPOINT_PERIOD_KEY;
    public static final long DFS_NAMENODE_CHECKPOINT_PERIOD_DEFAULT = 3600;
    public static final String DFS_NAMENODE_CHECKPOINT_TXNS_KEY = "dfs.namenode.checkpoint.txns";
    public static final long DFS_NAMENODE_CHECKPOINT_TXNS_DEFAULT = 1000000;
    public static final String DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_KEY = "dfs.namenode.checkpoint.max-retries";
    public static final int DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_DEFAULT = 3;
    public static final String DFS_NAMENODE_MISSING_CHECKPOINT_PERIODS_BEFORE_SHUTDOWN_KEY = "dfs.namenode.missing.checkpoint.periods.before.shutdown";
    public static final int DFS_NAMENODE_MISSING_CHECKPOINT_PERIODS_BEFORE_SHUTDOWN_DEFAULT = 3;
    public static final String DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_KEY;
    public static final int DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_DEFAULT = 5 * 60 * 1000;
    public static final String DFS_NAMENODE_TOLERATE_HEARTBEAT_MULTIPLIER_KEY = "dfs.namenode.tolerate.heartbeat.multiplier";
    public static final int DFS_NAMENODE_TOLERATE_HEARTBEAT_MULTIPLIER_DEFAULT = 4;
    public static final String DFS_NAMENODE_ACCESSTIME_PRECISION_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_ACCESSTIME_PRECISION_KEY;
    public static final long DFS_NAMENODE_ACCESSTIME_PRECISION_DEFAULT = 3600000;
    public static final String DFS_NAMENODE_REDUNDANCY_CONSIDERLOAD_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_REDUNDANCY_CONSIDERLOAD_KEY;
    public static final boolean DFS_NAMENODE_REDUNDANCY_CONSIDERLOAD_DEFAULT = true;
    public static final String DFS_NAMENODE_REDUNDANCY_CONSIDERLOAD_FACTOR = "dfs.namenode.redundancy.considerLoad.factor";
    public static final double DFS_NAMENODE_REDUNDANCY_CONSIDERLOAD_FACTOR_DEFAULT = 2.0;
    public static final String DFS_NAMENODE_REDUNDANCY_INTERVAL_SECONDS_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_REDUNDANCY_INTERVAL_SECONDS_KEY;
    public static final int DFS_NAMENODE_REDUNDANCY_INTERVAL_SECONDS_DEFAULT = 3;
    public static final String DFS_NAMENODE_REPLICATION_MIN_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_REPLICATION_MIN_KEY;
    public static final int DFS_NAMENODE_REPLICATION_MIN_DEFAULT = 1;
    public static final String DFS_NAMENODE_FILE_CLOSE_NUM_COMMITTED_ALLOWED_KEY = "dfs.namenode.file.close.num-committed-allowed";
    public static final int DFS_NAMENODE_FILE_CLOSE_NUM_COMMITTED_ALLOWED_DEFAULT = 0;
    public static final String DFS_NAMENODE_STRIPE_MIN_KEY = "dfs.namenode.stripe.min";
    public static final int DFS_NAMENODE_STRIPE_MIN_DEFAULT = 1;
    public static final String DFS_NAMENODE_SAFEMODE_REPLICATION_MIN_KEY = "dfs.namenode.safemode.replication.min";

    public static final String DFS_NAMENODE_RECONSTRUCTION_PENDING_TIMEOUT_SEC_KEY = "dfs.namenode.reconstruction.pending.timeout-sec";
    public static final int DFS_NAMENODE_RECONSTRUCTION_PENDING_TIMEOUT_SEC_DEFAULT = 300;

    public static final String DFS_NAMENODE_MAINTENANCE_REPLICATION_MIN_KEY = "dfs.namenode.maintenance.replication.min";
    public static final int DFS_NAMENODE_MAINTENANCE_REPLICATION_MIN_DEFAULT = 1;

    public static final String DFS_NAMENODE_MAX_CORRUPT_FILE_BLOCKS_RETURNED_KEY = "dfs.namenode.max-corrupt-file-blocks-returned";
    public static final int DFS_NAMENODE_MAX_CORRUPT_FILE_BLOCKS_RETURNED_DEFAULT = 100;

    public static final String DFS_NAMENODE_REPLICATION_MAX_STREAMS_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_REPLICATION_MAX_STREAMS_KEY;
    public static final int DFS_NAMENODE_REPLICATION_MAX_STREAMS_DEFAULT = 2;
    public static final String DFS_NAMENODE_REPLICATION_STREAMS_HARD_LIMIT_KEY = "dfs.namenode.replication.max-streams-hard-limit";
    public static final int DFS_NAMENODE_REPLICATION_STREAMS_HARD_LIMIT_DEFAULT = 4;
    public static final String DFS_NAMENODE_STORAGEINFO_DEFRAGMENT_INTERVAL_MS_KEY = "dfs.namenode.storageinfo.defragment.interval.ms";
    public static final int DFS_NAMENODE_STORAGEINFO_DEFRAGMENT_INTERVAL_MS_DEFAULT = 10 * 60 * 1000;
    public static final String DFS_NAMENODE_STORAGEINFO_DEFRAGMENT_TIMEOUT_MS_KEY = "dfs.namenode.storageinfo.defragment.timeout.ms";
    public static final int DFS_NAMENODE_STORAGEINFO_DEFRAGMENT_TIMEOUT_MS_DEFAULT = 4;
    public static final String DFS_NAMENODE_STORAGEINFO_DEFRAGMENT_RATIO_KEY = "dfs.namenode.storageinfo.defragment.ratio";
    public static final double DFS_NAMENODE_STORAGEINFO_DEFRAGMENT_RATIO_DEFAULT = 0.75;
    public static final String DFS_WEBHDFS_AUTHENTICATION_FILTER_KEY = "dfs.web.authentication.filter";
    /* Phrased as below to avoid javac inlining as a constant, to match the behavior when
       this was AuthFilter.class.getName(). Note that if you change the import for AuthFilter, you
       need to update the literal here as well as TestDFSConfigKeys.
     */
    public static final String DFS_WEBHDFS_AUTHENTICATION_FILTER_DEFAULT = "org.apache.hadoop.hdfs.web.AuthFilter";
    @Deprecated
    public static final String DFS_WEBHDFS_USER_PATTERN_KEY = HdfsClientConfigKeys.DFS_WEBHDFS_USER_PATTERN_KEY;
    @Deprecated
    public static final String DFS_WEBHDFS_USER_PATTERN_DEFAULT = HdfsClientConfigKeys.DFS_WEBHDFS_USER_PATTERN_DEFAULT;
    public static final String DFS_PERMISSIONS_ENABLED_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_PERMISSIONS_ENABLED_KEY;
    public static final boolean DFS_PERMISSIONS_ENABLED_DEFAULT = true;
    public static final String DFS_PERMISSIONS_SUPERUSERGROUP_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_PERMISSIONS_SUPERUSERGROUP_KEY;
    public static final String DFS_PERMISSIONS_SUPERUSERGROUP_DEFAULT = "supergroup";
    public static final String DFS_NAMENODE_ACLS_ENABLED_KEY = "dfs.namenode.acls.enabled";
    public static final boolean DFS_NAMENODE_ACLS_ENABLED_DEFAULT = false;
    public static final String DFS_NAMENODE_POSIX_ACL_INHERITANCE_ENABLED_KEY = "dfs.namenode.posix.acl.inheritance.enabled";
    public static final boolean DFS_NAMENODE_POSIX_ACL_INHERITANCE_ENABLED_DEFAULT = true;
    public static final String DFS_REFORMAT_DISABLED = "dfs.reformat.disabled";
    public static final boolean DFS_REFORMAT_DISABLED_DEFAULT = false;

    public static final String DFS_NAMENODE_XATTRS_ENABLED_KEY = "dfs.namenode.xattrs.enabled";
    public static final boolean DFS_NAMENODE_XATTRS_ENABLED_DEFAULT = true;
    public static final String DFS_ADMIN = "dfs.cluster.administrators";
    public static final String DFS_SERVER_HTTPS_KEYSTORE_RESOURCE_KEY = "dfs.https.server.keystore.resource";
    public static final String DFS_SERVER_HTTPS_KEYSTORE_RESOURCE_DEFAULT = "ssl-server.xml";
    public static final String DFS_SERVER_HTTPS_KEYPASSWORD_KEY = "ssl.server.keystore.keypassword";
    public static final String DFS_SERVER_HTTPS_KEYSTORE_PASSWORD_KEY = "ssl.server.keystore.password";
    public static final String DFS_SERVER_HTTPS_KEYSTORE_LOCATION_KEY = "ssl.server.keystore.location";
    public static final String DFS_SERVER_HTTPS_TRUSTSTORE_LOCATION_KEY = "ssl.server.truststore.location";
    public static final String DFS_SERVER_HTTPS_TRUSTSTORE_PASSWORD_KEY = "ssl.server.truststore.password";
    public static final String DFS_NAMENODE_NAME_DIR_RESTORE_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_NAME_DIR_RESTORE_KEY;
    public static final boolean DFS_NAMENODE_NAME_DIR_RESTORE_DEFAULT = false;
    public static final String DFS_NAMENODE_SUPPORT_ALLOW_FORMAT_KEY = "dfs.namenode.support.allow.format";
    public static final boolean DFS_NAMENODE_SUPPORT_ALLOW_FORMAT_DEFAULT = true;
    public static final String DFS_NAMENODE_NUM_CHECKPOINTS_RETAINED_KEY = "dfs.namenode.num.checkpoints.retained";
    public static final int DFS_NAMENODE_NUM_CHECKPOINTS_RETAINED_DEFAULT = 2;
    public static final String DFS_NAMENODE_NUM_EXTRA_EDITS_RETAINED_KEY = "dfs.namenode.num.extra.edits.retained";
    public static final int DFS_NAMENODE_NUM_EXTRA_EDITS_RETAINED_DEFAULT = 1000000; //1M
    public static final String DFS_NAMENODE_MAX_EXTRA_EDITS_SEGMENTS_RETAINED_KEY = "dfs.namenode.max.extra.edits.segments.retained";
    public static final int DFS_NAMENODE_MAX_EXTRA_EDITS_SEGMENTS_RETAINED_DEFAULT = 10000; // 10k
    public static final String DFS_NAMENODE_MIN_SUPPORTED_DATANODE_VERSION_KEY = "dfs.namenode.min.supported.datanode.version";
    public static final String DFS_NAMENODE_MIN_SUPPORTED_DATANODE_VERSION_DEFAULT = "2.1.0-beta";

    public static final String DFS_NAMENODE_EDITS_DIR_MINIMUM_KEY = "dfs.namenode.edits.dir.minimum";
    public static final int DFS_NAMENODE_EDITS_DIR_MINIMUM_DEFAULT = 1;
    public static final String DFS_NAMENODE_QUOTA_INIT_THREADS_KEY = "dfs.namenode.quota.init-threads";
    public static final int DFS_NAMENODE_QUOTA_INIT_THREADS_DEFAULT = 4;

    public static final String DFS_NAMENODE_EDIT_LOG_AUTOROLL_MULTIPLIER_THRESHOLD = "dfs.namenode.edit.log.autoroll.multiplier.threshold";
    public static final float DFS_NAMENODE_EDIT_LOG_AUTOROLL_MULTIPLIER_THRESHOLD_DEFAULT = 2.0f;
    public static final String DFS_NAMENODE_EDIT_LOG_AUTOROLL_CHECK_INTERVAL_MS = "dfs.namenode.edit.log.autoroll.check.interval.ms";
    public static final int DFS_NAMENODE_EDIT_LOG_AUTOROLL_CHECK_INTERVAL_MS_DEFAULT = 5 * 60 * 1000;

    public static final String DFS_NAMENODE_LAZY_PERSIST_FILE_SCRUB_INTERVAL_SEC = "dfs.namenode.lazypersist.file.scrub.interval.sec";
    public static final int DFS_NAMENODE_LAZY_PERSIST_FILE_SCRUB_INTERVAL_SEC_DEFAULT = 5 * 60;

    public static final String DFS_NAMENODE_EDITS_NOEDITLOGCHANNELFLUSH = "dfs.namenode.edits.noeditlogchannelflush";
    public static final boolean DFS_NAMENODE_EDITS_NOEDITLOGCHANNELFLUSH_DEFAULT = false;

    public static final String DFS_NAMENODE_EDITS_ASYNC_LOGGING = "dfs.namenode.edits.asynclogging";
    public static final boolean DFS_NAMENODE_EDITS_ASYNC_LOGGING_DEFAULT = true;

    public static final String DFS_NAMENODE_PROVIDED_ENABLED = "dfs.namenode.provided.enabled";
    public static final boolean DFS_NAMENODE_PROVIDED_ENABLED_DEFAULT = false;

    public static final String DFS_PROVIDER_STORAGEUUID = "dfs.provided.storage.id";
    public static final String DFS_PROVIDER_STORAGEUUID_DEFAULT = "DS-PROVIDED";
    public static final String DFS_PROVIDED_ALIASMAP_CLASS = "dfs.provided.aliasmap.class";
    public static final String DFS_PROVIDED_ALIASMAP_LOAD_RETRIES = "dfs.provided.aliasmap.load.retries";

    public static final String DFS_PROVIDED_ALIASMAP_TEXT_DELIMITER = "dfs.provided.aliasmap.text.delimiter";
    public static final String DFS_PROVIDED_ALIASMAP_TEXT_DELIMITER_DEFAULT = ",";

    public static final String DFS_PROVIDED_ALIASMAP_TEXT_READ_FILE = "dfs.provided.aliasmap.text.read.file";
    public static final String DFS_PROVIDED_ALIASMAP_TEXT_READ_FILE_DEFAULT = "file:///tmp/blocks.csv";

    public static final String DFS_PROVIDED_ALIASMAP_TEXT_CODEC = "dfs.provided.aliasmap.text.codec";
    public static final String DFS_PROVIDED_ALIASMAP_TEXT_WRITE_DIR = "dfs.provided.aliasmap.text.write.dir";
    public static final String DFS_PROVIDED_ALIASMAP_TEXT_WRITE_DIR_DEFAULT = "file:///tmp/";

    public static final String DFS_PROVIDED_ALIASMAP_LEVELDB_PATH = "dfs.provided.aliasmap.leveldb.path";

    public static final String DFS_LIST_LIMIT = "dfs.ls.limit";
    public static final int DFS_LIST_LIMIT_DEFAULT = 1000;
    public static final String DFS_CONTENT_SUMMARY_LIMIT_KEY = "dfs.content-summary.limit";
    public static final int DFS_CONTENT_SUMMARY_LIMIT_DEFAULT = 5000;
    public static final String DFS_CONTENT_SUMMARY_SLEEP_MICROSEC_KEY = "dfs.content-summary.sleep-microsec";
    public static final long DFS_CONTENT_SUMMARY_SLEEP_MICROSEC_DEFAULT = 500;
    public static final String DFS_DATANODE_FAILED_VOLUMES_TOLERATED_KEY = "dfs.datanode.failed.volumes.tolerated";
    public static final int DFS_DATANODE_FAILED_VOLUMES_TOLERATED_DEFAULT = 0;
    public static final String DFS_DATANODE_VOLUMES_REPLICA_ADD_THREADPOOL_SIZE_KEY = "dfs.datanode.volumes.replica-add.threadpool.size";
    public static final String DFS_DATANODE_SYNCONCLOSE_KEY = "dfs.datanode.synconclose";
    public static final boolean DFS_DATANODE_SYNCONCLOSE_DEFAULT = false;
    public static final String DFS_DATANODE_SOCKET_REUSE_KEEPALIVE_KEY = "dfs.datanode.socket.reuse.keepalive";
    public static final int DFS_DATANODE_SOCKET_REUSE_KEEPALIVE_DEFAULT = 4000;
    public static final String DFS_DATANODE_OOB_TIMEOUT_KEY = "dfs.datanode.oob.timeout-ms";
    public static final String DFS_DATANODE_OOB_TIMEOUT_DEFAULT = "1500,0,0,0"; // OOB_TYPE1, OOB_TYPE2, OOB_TYPE3, OOB_TYPE4

    public static final String DFS_DATANODE_CACHE_REVOCATION_TIMEOUT_MS = "dfs.datanode.cache.revocation.timeout.ms";
    public static final long DFS_DATANODE_CACHE_REVOCATION_TIMEOUT_MS_DEFAULT = 900000L;

    public static final String DFS_DATANODE_CACHE_REVOCATION_POLLING_MS = "dfs.datanode.cache.revocation.polling.ms";
    public static final long DFS_DATANODE_CACHE_REVOCATION_POLLING_MS_DEFAULT = 500L;

    public static final String DFS_NAMENODE_DATANODE_REGISTRATION_IP_HOSTNAME_CHECK_KEY = "dfs.namenode.datanode.registration.ip-hostname-check";
    public static final boolean DFS_NAMENODE_DATANODE_REGISTRATION_IP_HOSTNAME_CHECK_DEFAULT = true;

    public static final String DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES = "dfs.namenode.list.cache.pools.num.responses";
    public static final int DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES_DEFAULT = 100;
    public static final String DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES = "dfs.namenode.list.cache.directives.num.responses";
    public static final int DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES_DEFAULT = 100;
    public static final String DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS = "dfs.namenode.path.based.cache.refresh.interval.ms";
    public static final long DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS_DEFAULT = 30000L;
    public static final String DFS_NAMENODE_CACHING_ENABLED_KEY = "dfs.namenode.caching.enabled";
    public static final boolean DFS_NAMENODE_CACHING_ENABLED_DEFAULT = true;

    /** Pending period of block deletion since NameNode startup */
    public static final String DFS_NAMENODE_STARTUP_DELAY_BLOCK_DELETION_SEC_KEY = "dfs.namenode.startup.delay.block.deletion.sec";
    public static final long DFS_NAMENODE_STARTUP_DELAY_BLOCK_DELETION_SEC_DEFAULT = 0L;

    /** Block deletion increment. */
    public static final String DFS_NAMENODE_BLOCK_DELETION_INCREMENT_KEY = "dfs.namenode.block.deletion.increment";
    public static final int DFS_NAMENODE_BLOCK_DELETION_INCREMENT_DEFAULT = 1000;

    public static final String DFS_NAMENODE_SNAPSHOT_CAPTURE_OPENFILES = HdfsClientConfigKeys.DFS_NAMENODE_SNAPSHOT_CAPTURE_OPENFILES;
    public static final boolean DFS_NAMENODE_SNAPSHOT_CAPTURE_OPENFILES_DEFAULT = HdfsClientConfigKeys.DFS_NAMENODE_SNAPSHOT_CAPTURE_OPENFILES_DEFAULT;

    public static final String DFS_NAMENODE_SNAPSHOT_SKIP_CAPTURE_ACCESSTIME_ONLY_CHANGE = "dfs.namenode.snapshot.skip.capture.accesstime-only-change";
    public static final boolean DFS_NAMENODE_SNAPSHOT_SKIP_CAPTURE_ACCESSTIME_ONLY_CHANGE_DEFAULT = false;

    public static final String DFS_NAMENODE_SNAPSHOT_DIFF_ALLOW_SNAP_ROOT_DESCENDANT = "dfs.namenode.snapshotdiff.allow.snap-root-descendant";
    public static final boolean DFS_NAMENODE_SNAPSHOT_DIFF_ALLOW_SNAP_ROOT_DESCENDANT_DEFAULT = true;

    public static final String DFS_NAMENODE_SNAPSHOT_DIFF_LISTING_LIMIT = "dfs.namenode.snapshotdiff.listing.limit";
    public static final int DFS_NAMENODE_SNAPSHOT_DIFF_LISTING_LIMIT_DEFAULT = 1000;

    public static final String DFS_NAMENODE_SNAPSHOT_MAX_LIMIT = "dfs.namenode.snapshot.max.limit";

    public static final int DFS_NAMENODE_SNAPSHOT_MAX_LIMIT_DEFAULT = 65536;
    public static final String DFS_NAMENODE_SNAPSHOT_SKIPLIST_SKIP_INTERVAL = "dfs.namenode.snapshot.skiplist.interval";
    public static final int DFS_NAMENODE_SNAPSHOT_SKIPLIST_SKIP_INTERVAL_DEFAULT = 10;
    public static final String DFS_NAMENODE_SNAPSHOT_SKIPLIST_MAX_LEVELS = "dfs.namenode.snapshot.skiplist.max.levels";
    public static final int DFS_NAMENODE_SNAPSHOT_SKIPLIST_MAX_SKIP_LEVELS_DEFAULT = 0;

    // Whether to enable datanode's stale state detection and usage for reads
    public static final String DFS_NAMENODE_AVOID_STALE_DATANODE_FOR_READ_KEY = "dfs.namenode.avoid.read.stale.datanode";
    public static final boolean DFS_NAMENODE_AVOID_STALE_DATANODE_FOR_READ_DEFAULT = false;
    // Whether to enable datanode's stale state detection and usage for writes
    public static final String DFS_NAMENODE_AVOID_STALE_DATANODE_FOR_WRITE_KEY = "dfs.namenode.avoid.write.stale.datanode";
    public static final boolean DFS_NAMENODE_AVOID_STALE_DATANODE_FOR_WRITE_DEFAULT = false;
    // The default value of the time interval for marking datanodes as stale
    public static final String DFS_NAMENODE_STALE_DATANODE_INTERVAL_KEY = "dfs.namenode.stale.datanode.interval";
    public static final long DFS_NAMENODE_STALE_DATANODE_INTERVAL_DEFAULT = 30 * 1000; // 30s
    // The stale interval cannot be too small since otherwise this may cause too frequent churn on stale states. 
    // This value uses the times of heartbeat interval to define the minimum value for stale interval.  
    public static final String DFS_NAMENODE_STALE_DATANODE_MINIMUM_INTERVAL_KEY = "dfs.namenode.stale.datanode.minimum.interval";
    public static final int DFS_NAMENODE_STALE_DATANODE_MINIMUM_INTERVAL_DEFAULT = 3; // i.e. min_interval is 3 * heartbeat_interval = 9s

    // When the percentage of stale datanodes reaches this ratio,
    // allow writing to stale nodes to prevent hotspots.
    public static final String DFS_NAMENODE_USE_STALE_DATANODE_FOR_WRITE_RATIO_KEY = "dfs.namenode.write.stale.datanode.ratio";
    public static final float DFS_NAMENODE_USE_STALE_DATANODE_FOR_WRITE_RATIO_DEFAULT = 0.5f;

    // Number of blocks to rescan for each iteration of postponedMisreplicatedBlocks.
    public static final String DFS_NAMENODE_BLOCKS_PER_POSTPONEDBLOCKS_RESCAN_KEY = "dfs.namenode.blocks.per.postponedblocks.rescan";
    public static final long DFS_NAMENODE_BLOCKS_PER_POSTPONEDBLOCKS_RESCAN_KEY_DEFAULT = 10000;

    // Replication monitoring related keys
    public static final String DFS_NAMENODE_INVALIDATE_WORK_PCT_PER_ITERATION = "dfs.namenode.invalidate.work.pct.per.iteration";
    public static final float DFS_NAMENODE_INVALIDATE_WORK_PCT_PER_ITERATION_DEFAULT = 0.32f;
    public static final String DFS_NAMENODE_REPLICATION_WORK_MULTIPLIER_PER_ITERATION = "dfs.namenode.replication.work.multiplier.per.iteration";
    public static final int DFS_NAMENODE_REPLICATION_WORK_MULTIPLIER_PER_ITERATION_DEFAULT = 2;

    //Delegation token related keys
    public static final String DFS_NAMENODE_DELEGATION_KEY_UPDATE_INTERVAL_KEY = "dfs.namenode.delegation.key.update-interval";
    public static final long DFS_NAMENODE_DELEGATION_KEY_UPDATE_INTERVAL_DEFAULT = 24 * 60 * 60 * 1000; // 1 day
    public static final String DFS_NAMENODE_DELEGATION_TOKEN_RENEW_INTERVAL_KEY = "dfs.namenode.delegation.token.renew-interval";
    public static final long DFS_NAMENODE_DELEGATION_TOKEN_RENEW_INTERVAL_DEFAULT = 24 * 60 * 60 * 1000; // 1 day
    public static final String DFS_NAMENODE_DELEGATION_TOKEN_MAX_LIFETIME_KEY = "dfs.namenode.delegation.token.max-lifetime";
    public static final long DFS_NAMENODE_DELEGATION_TOKEN_MAX_LIFETIME_DEFAULT = 7 * 24 * 60 * 60 * 1000; // 7 days
    public static final String DFS_NAMENODE_DELEGATION_TOKEN_ALWAYS_USE_KEY = "dfs.namenode.delegation.token.always-use"; // for tests
    public static final boolean DFS_NAMENODE_DELEGATION_TOKEN_ALWAYS_USE_DEFAULT = false;

    //Filesystem limit keys
    public static final String DFS_NAMENODE_MAX_COMPONENT_LENGTH_KEY = "dfs.namenode.fs-limits.max-component-length";
    public static final int DFS_NAMENODE_MAX_COMPONENT_LENGTH_DEFAULT = 255;
    public static final String DFS_NAMENODE_MAX_DIRECTORY_ITEMS_KEY = "dfs.namenode.fs-limits.max-directory-items";
    public static final int DFS_NAMENODE_MAX_DIRECTORY_ITEMS_DEFAULT = 1024 * 1024;
    public static final String DFS_NAMENODE_MIN_BLOCK_SIZE_KEY = "dfs.namenode.fs-limits.min-block-size";
    public static final long DFS_NAMENODE_MIN_BLOCK_SIZE_DEFAULT = 1024 * 1024;
    public static final String DFS_NAMENODE_MAX_BLOCKS_PER_FILE_KEY = "dfs.namenode.fs-limits.max-blocks-per-file";
    public static final long DFS_NAMENODE_MAX_BLOCKS_PER_FILE_DEFAULT = 10 * 1000;
    public static final String DFS_NAMENODE_MAX_XATTRS_PER_INODE_KEY = "dfs.namenode.fs-limits.max-xattrs-per-inode";
    public static final int DFS_NAMENODE_MAX_XATTRS_PER_INODE_DEFAULT = 32;
    public static final String DFS_NAMENODE_MAX_XATTR_SIZE_KEY = "dfs.namenode.fs-limits.max-xattr-size";
    public static final int DFS_NAMENODE_MAX_XATTR_SIZE_DEFAULT = 16384;
    public static final int DFS_NAMENODE_MAX_XATTR_SIZE_HARD_LIMIT = 32768;

    public static final String DFS_NAMENODE_LEASE_RECHECK_INTERVAL_MS_KEY = "dfs.namenode.lease-recheck-interval-ms";
    public static final long DFS_NAMENODE_LEASE_RECHECK_INTERVAL_MS_DEFAULT = 2000;
    public static final String DFS_NAMENODE_MAX_LOCK_HOLD_TO_RELEASE_LEASE_MS_KEY = "dfs.namenode.max-lock-hold-to-release-lease-ms";
    public static final long DFS_NAMENODE_MAX_LOCK_HOLD_TO_RELEASE_LEASE_MS_DEFAULT = 25;

    public static final String DFS_NAMENODE_FSLOCK_FAIR_KEY = "dfs.namenode.fslock.fair";
    public static final boolean DFS_NAMENODE_FSLOCK_FAIR_DEFAULT = true;

    public static final String DFS_NAMENODE_LOCK_DETAILED_METRICS_KEY = "dfs.namenode.lock.detailed-metrics.enabled";
    public static final boolean DFS_NAMENODE_LOCK_DETAILED_METRICS_DEFAULT = false;
    // Threshold for how long namenode locks must be held for the
    // event to be logged
    public static final String DFS_NAMENODE_WRITE_LOCK_REPORTING_THRESHOLD_MS_KEY = "dfs.namenode.write-lock-reporting-threshold-ms";
    public static final long DFS_NAMENODE_WRITE_LOCK_REPORTING_THRESHOLD_MS_DEFAULT = 5000L;
    public static final String DFS_NAMENODE_READ_LOCK_REPORTING_THRESHOLD_MS_KEY = "dfs.namenode.read-lock-reporting-threshold-ms";
    public static final long DFS_NAMENODE_READ_LOCK_REPORTING_THRESHOLD_MS_DEFAULT = 5000L;
    // Threshold for how long the lock warnings must be suppressed
    public static final String DFS_LOCK_SUPPRESS_WARNING_INTERVAL_KEY = "dfs.lock.suppress.warning.interval";
    public static final long DFS_LOCK_SUPPRESS_WARNING_INTERVAL_DEFAULT = 10000; //ms

    public static final String DFS_UPGRADE_DOMAIN_FACTOR = "dfs.namenode.upgrade.domain.factor";
    public static final int DFS_UPGRADE_DOMAIN_FACTOR_DEFAULT = DFS_REPLICATION_DEFAULT;

    //Following keys have no defaults
    public static final String DFS_DATANODE_DATA_DIR_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_DATANODE_DATA_DIR_KEY;
    public static final int DFS_NAMENODE_HTTPS_PORT_DEFAULT = HdfsClientConfigKeys.DFS_NAMENODE_HTTPS_PORT_DEFAULT;
    public static final String DFS_NAMENODE_HTTPS_ADDRESS_KEY = HdfsClientConfigKeys.DFS_NAMENODE_HTTPS_ADDRESS_KEY;
    public static final String DFS_NAMENODE_HTTPS_BIND_HOST_KEY = "dfs.namenode.https-bind-host";
    public static final String DFS_NAMENODE_HTTPS_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_NAMENODE_HTTPS_PORT_DEFAULT;
    public static final String DFS_NAMENODE_NAME_DIR_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_NAME_DIR_KEY;
    public static final String DFS_NAMENODE_EDITS_DIR_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_EDITS_DIR_KEY;
    public static final String DFS_NAMENODE_SHARED_EDITS_DIR_KEY = "dfs.namenode.shared.edits.dir";
    public static final String DFS_NAMENODE_EDITS_PLUGIN_PREFIX = "dfs.namenode.edits.journal-plugin";
    public static final String DFS_NAMENODE_EDITS_DIR_REQUIRED_KEY = "dfs.namenode.edits.dir.required";
    public static final String DFS_NAMENODE_EDITS_DIR_DEFAULT = "file:///tmp/hadoop/dfs/name";
    public static final String DFS_METRICS_SESSION_ID_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_METRICS_SESSION_ID_KEY;
    public static final String DFS_METRICS_PERCENTILES_INTERVALS_KEY = "dfs.metrics.percentiles.intervals";

    public static final String DFS_DATANODE_PEER_STATS_ENABLED_KEY = "dfs.datanode.peer.stats.enabled";
    public static final boolean DFS_DATANODE_PEER_STATS_ENABLED_DEFAULT = false;
    public static final String DFS_DATANODE_HOST_NAME_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_DATANODE_HOST_NAME_KEY;
    public static final String DFS_NAMENODE_CHECKPOINT_DIR_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_CHECKPOINT_DIR_KEY;
    public static final String DFS_NAMENODE_CHECKPOINT_EDITS_DIR_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMENODE_CHECKPOINT_EDITS_DIR_KEY;
    public static final String DFS_NAMENODE_HOSTS_PROVIDER_CLASSNAME_KEY = "dfs.namenode.hosts.provider.classname";
    public static final String DFS_HOSTS = "dfs.hosts";
    public static final String DFS_HOSTS_EXCLUDE = "dfs.hosts.exclude";
    public static final String DFS_NAMENODE_AUDIT_LOGGERS_KEY = "dfs.namenode.audit.loggers";
    public static final String DFS_NAMENODE_DEFAULT_AUDIT_LOGGER_NAME = "default";
    public static final String DFS_NAMENODE_AUDIT_LOG_TOKEN_TRACKING_ID_KEY = "dfs.namenode.audit.log.token.tracking.id";
    public static final boolean DFS_NAMENODE_AUDIT_LOG_TOKEN_TRACKING_ID_DEFAULT = false;
    public static final String DFS_NAMENODE_AUDIT_LOG_ASYNC_KEY = "dfs.namenode.audit.log.async";
    public static final boolean DFS_NAMENODE_AUDIT_LOG_ASYNC_DEFAULT = false;
    public static final String DFS_NAMENODE_AUDIT_LOG_DEBUG_CMDLIST = "dfs.namenode.audit.log.debug.cmdlist";
    public static final String DFS_NAMENODE_METRICS_LOGGER_PERIOD_SECONDS_KEY = "dfs.namenode.metrics.logger.period.seconds";
    public static final int DFS_NAMENODE_METRICS_LOGGER_PERIOD_SECONDS_DEFAULT = 600;
    public static final String DFS_DATANODE_METRICS_LOGGER_PERIOD_SECONDS_KEY = "dfs.datanode.metrics.logger.period.seconds";
    public static final int DFS_DATANODE_METRICS_LOGGER_PERIOD_SECONDS_DEFAULT = 600;

    public static final String DFS_BALANCER_MOVEDWINWIDTH_KEY = "dfs.balancer.movedWinWidth";
    public static final long DFS_BALANCER_MOVEDWINWIDTH_DEFAULT = 5400 * 1000L;
    public static final String DFS_BALANCER_MOVERTHREADS_KEY = "dfs.balancer.moverThreads";
    public static final int DFS_BALANCER_MOVERTHREADS_DEFAULT = 1000;
    public static final String DFS_BALANCER_DISPATCHERTHREADS_KEY = "dfs.balancer.dispatcherThreads";
    public static final int DFS_BALANCER_DISPATCHERTHREADS_DEFAULT = 200;
    public static final String DFS_BALANCER_MAX_SIZE_TO_MOVE_KEY = "dfs.balancer.max-size-to-move";
    public static final long DFS_BALANCER_MAX_SIZE_TO_MOVE_DEFAULT = 10L * 1024 * 1024 * 1024;
    public static final String DFS_BALANCER_GETBLOCKS_SIZE_KEY = "dfs.balancer.getBlocks.size";
    public static final long DFS_BALANCER_GETBLOCKS_SIZE_DEFAULT = 2L * 1024 * 1024 * 1024; // 2GB
    public static final String DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_KEY = "dfs.balancer.getBlocks.min-block-size";
    public static final long DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_DEFAULT = 10L * 1024 * 1024; // 10MB
    public static final String DFS_BALANCER_KEYTAB_ENABLED_KEY = "dfs.balancer.keytab.enabled";
    public static final boolean DFS_BALANCER_KEYTAB_ENABLED_DEFAULT = false;
    public static final String DFS_BALANCER_ADDRESS_KEY = "dfs.balancer.address";
    public static final String DFS_BALANCER_ADDRESS_DEFAULT = "0.0.0.0:0";
    public static final String DFS_BALANCER_KEYTAB_FILE_KEY = "dfs.balancer.keytab.file";
    public static final String DFS_BALANCER_KERBEROS_PRINCIPAL_KEY = "dfs.balancer.kerberos.principal";
    public static final String DFS_BALANCER_BLOCK_MOVE_TIMEOUT = "dfs.balancer.block-move.timeout";
    public static final int DFS_BALANCER_BLOCK_MOVE_TIMEOUT_DEFAULT = 0;
    public static final String DFS_BALANCER_MAX_NO_MOVE_INTERVAL_KEY = "dfs.balancer.max-no-move-interval";
    public static final int DFS_BALANCER_MAX_NO_MOVE_INTERVAL_DEFAULT = 60 * 1000; // One minute
    public static final String DFS_BALANCER_MAX_ITERATION_TIME_KEY = "dfs.balancer.max-iteration-time";
    public static final long DFS_BALANCER_MAX_ITERATION_TIME_DEFAULT = 20 * 60 * 1000L; // 20 mins

    public static final String DFS_MOVER_MOVEDWINWIDTH_KEY = "dfs.mover.movedWinWidth";
    public static final long DFS_MOVER_MOVEDWINWIDTH_DEFAULT = 5400 * 1000L;
    public static final String DFS_MOVER_MOVERTHREADS_KEY = "dfs.mover.moverThreads";
    public static final int DFS_MOVER_MOVERTHREADS_DEFAULT = 1000;
    public static final String DFS_MOVER_RETRY_MAX_ATTEMPTS_KEY = "dfs.mover.retry.max.attempts";
    public static final int DFS_MOVER_RETRY_MAX_ATTEMPTS_DEFAULT = 10;
    public static final String DFS_MOVER_KEYTAB_ENABLED_KEY = "dfs.mover.keytab.enabled";
    public static final boolean DFS_MOVER_KEYTAB_ENABLED_DEFAULT = false;
    public static final String DFS_MOVER_ADDRESS_KEY = "dfs.mover.address";
    public static final String DFS_MOVER_ADDRESS_DEFAULT = "0.0.0.0:0";
    public static final String DFS_MOVER_KEYTAB_FILE_KEY = "dfs.mover.keytab.file";
    public static final String DFS_MOVER_KERBEROS_PRINCIPAL_KEY = "dfs.mover.kerberos.principal";
    public static final String DFS_MOVER_MAX_NO_MOVE_INTERVAL_KEY = "dfs.mover.max-no-move-interval";
    public static final int DFS_MOVER_MAX_NO_MOVE_INTERVAL_DEFAULT = 60 * 1000; // One minute

    // StoragePolicySatisfier (SPS) related configurations
    public static final String DFS_STORAGE_POLICY_SATISFIER_MODE_KEY = "dfs.storage.policy.satisfier.mode";
    public static final String DFS_STORAGE_POLICY_SATISFIER_MODE_DEFAULT = StoragePolicySatisfierMode.NONE
            .toString();
    public static final String DFS_STORAGE_POLICY_SATISFIER_QUEUE_LIMIT_KEY = "dfs.storage.policy.satisfier.queue.limit";
    public static final int DFS_STORAGE_POLICY_SATISFIER_QUEUE_LIMIT_DEFAULT = 1000;
    public static final String DFS_SPS_WORK_MULTIPLIER_PER_ITERATION = "dfs.storage.policy.satisfier.work.multiplier.per.iteration";
    public static final int DFS_SPS_WORK_MULTIPLIER_PER_ITERATION_DEFAULT = 1;
    public static final String DFS_STORAGE_POLICY_SATISFIER_RECHECK_TIMEOUT_MILLIS_KEY = "dfs.storage.policy.satisfier.recheck.timeout.millis";
    public static final int DFS_STORAGE_POLICY_SATISFIER_RECHECK_TIMEOUT_MILLIS_DEFAULT = 1 * 60 * 1000;
    public static final String DFS_STORAGE_POLICY_SATISFIER_SELF_RETRY_TIMEOUT_MILLIS_KEY = "dfs.storage.policy.satisfier.self.retry.timeout.millis";
    public static final int DFS_STORAGE_POLICY_SATISFIER_SELF_RETRY_TIMEOUT_MILLIS_DEFAULT = 5 * 60 * 1000;
    public static final String DFS_STORAGE_POLICY_SATISFIER_MAX_RETRY_ATTEMPTS_KEY = "dfs.storage.policy.satisfier.retry.max.attempts";
    public static final int DFS_STORAGE_POLICY_SATISFIER_MAX_RETRY_ATTEMPTS_DEFAULT = 3;
    public static final String DFS_SPS_MAX_OUTSTANDING_PATHS_KEY = "dfs.storage.policy.satisfier.max.outstanding.paths";
    public static final int DFS_SPS_MAX_OUTSTANDING_PATHS_DEFAULT = 10000;
    // SPS datanode cache config, defaulting to 5mins.
    public static final String DFS_SPS_DATANODE_CACHE_REFRESH_INTERVAL_MS = "dfs.storage.policy.satisfier.datanode.cache.refresh.interval.ms";
    public static final long DFS_SPS_DATANODE_CACHE_REFRESH_INTERVAL_MS_DEFAULT = 300000L;

    // SPS keytab configurations, by default it is disabled.
    public static final String DFS_SPS_ADDRESS_KEY = "dfs.storage.policy.satisfier.address";
    public static final String DFS_SPS_ADDRESS_DEFAULT = "0.0.0.0:0";
    public static final String DFS_SPS_KEYTAB_FILE_KEY = "dfs.storage.policy.satisfier.keytab.file";
    public static final String DFS_SPS_KERBEROS_PRINCIPAL_KEY = "dfs.storage.policy.satisfier.kerberos.principal";

    public static final String DFS_DATANODE_ADDRESS_KEY = "dfs.datanode.address";
    public static final int DFS_DATANODE_DEFAULT_PORT = 9866;
    public static final String DFS_DATANODE_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_DATANODE_DEFAULT_PORT;
    public static final String DFS_DATANODE_DATA_DIR_PERMISSION_KEY = "dfs.datanode.data.dir.perm";
    public static final String DFS_DATANODE_DATA_DIR_PERMISSION_DEFAULT = "700";
    public static final String DFS_DATANODE_DIRECTORYSCAN_INTERVAL_KEY = "dfs.datanode.directoryscan.interval";
    public static final int DFS_DATANODE_DIRECTORYSCAN_INTERVAL_DEFAULT = 21600;
    public static final String DFS_DATANODE_DIRECTORYSCAN_THREADS_KEY = "dfs.datanode.directoryscan.threads";
    public static final int DFS_DATANODE_DIRECTORYSCAN_THREADS_DEFAULT = 1;

    public static final String DFS_DATANODE_DISK_CHECK_MIN_GAP_KEY = "dfs.datanode.disk.check.min.gap";
    public static final String DFS_DATANODE_DISK_CHECK_MIN_GAP_DEFAULT = "15m";

    public static final String DFS_DATANODE_DISK_CHECK_TIMEOUT_KEY = "dfs.datanode.disk.check.timeout";
    public static final String DFS_DATANODE_DISK_CHECK_TIMEOUT_DEFAULT = "10m";

    public static final String DFS_NAMENODE_EC_POLICIES_MAX_CELLSIZE_KEY = "dfs.namenode.ec.policies.max.cellsize";
    public static final int DFS_NAMENODE_EC_POLICIES_MAX_CELLSIZE_DEFAULT = 4 * 1024 * 1024;
    public static final String DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY = "dfs.namenode.ec.system.default.policy";
    public static final String DFS_NAMENODE_EC_SYSTEM_DEFAULT_POLICY_DEFAULT = "RS-6-3-1024k";
    public static final String DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_BUFFER_SIZE_KEY = "dfs.datanode.ec.reconstruction.stripedread.buffer.size";
    public static final int DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_BUFFER_SIZE_DEFAULT = 64 * 1024;
    public static final String DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_TIMEOUT_MILLIS_KEY = "dfs.datanode.ec.reconstruction.stripedread.timeout.millis";
    public static final int DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_TIMEOUT_MILLIS_DEFAULT = 5000; //5s
    public static final String DFS_DN_EC_RECONSTRUCTION_THREADS_KEY = "dfs.datanode.ec.reconstruction.threads";
    public static final int DFS_DN_EC_RECONSTRUCTION_THREADS_DEFAULT = 8;
    public static final String DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_KEY = "dfs.datanode.ec.reconstruction.xmits.weight";
    public static final float DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_DEFAULT = 0.5f;

    public static final String DFS_DATANODE_DIRECTORYSCAN_THROTTLE_LIMIT_MS_PER_SEC_KEY = "dfs.datanode.directoryscan.throttle.limit.ms.per.sec";
    public static final int DFS_DATANODE_DIRECTORYSCAN_THROTTLE_LIMIT_MS_PER_SEC_DEFAULT = 1000;
    public static final String DFS_DATANODE_DNS_INTERFACE_KEY = "dfs.datanode.dns.interface";
    public static final String DFS_DATANODE_DNS_INTERFACE_DEFAULT = "default";
    public static final String DFS_DATANODE_DNS_NAMESERVER_KEY = "dfs.datanode.dns.nameserver";
    public static final String DFS_DATANODE_DNS_NAMESERVER_DEFAULT = "default";
    public static final String DFS_DATANODE_DU_RESERVED_CALCULATOR_KEY = "dfs.datanode.du.reserved.calculator";
    public static final Class<? extends ReservedSpaceCalculator> DFS_DATANODE_DU_RESERVED_CALCULATOR_DEFAULT = ReservedSpaceCalculator.ReservedSpaceCalculatorAbsolute.class;
    public static final String DFS_DATANODE_DU_RESERVED_KEY = "dfs.datanode.du.reserved";
    public static final long DFS_DATANODE_DU_RESERVED_DEFAULT = 0;
    public static final String DFS_DATANODE_DU_RESERVED_PERCENTAGE_KEY = "dfs.datanode.du.reserved.pct";
    public static final int DFS_DATANODE_DU_RESERVED_PERCENTAGE_DEFAULT = 0;
    public static final String DFS_DATANODE_HANDLER_COUNT_KEY = "dfs.datanode.handler.count";
    public static final int DFS_DATANODE_HANDLER_COUNT_DEFAULT = 10;
    public static final String DFS_DATANODE_HTTP_ADDRESS_KEY = "dfs.datanode.http.address";
    public static final int DFS_DATANODE_HTTP_DEFAULT_PORT = 9864;
    public static final String DFS_DATANODE_HTTP_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_DATANODE_HTTP_DEFAULT_PORT;
    public static final String DFS_DATANODE_HTTP_INTERNAL_PROXY_PORT = "dfs.datanode.http.internal-proxy.port";
    public static final String DFS_DATANODE_MAX_RECEIVER_THREADS_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_DATANODE_MAX_RECEIVER_THREADS_KEY;
    public static final int DFS_DATANODE_MAX_RECEIVER_THREADS_DEFAULT = 4096;
    public static final String DFS_DATANODE_SCAN_PERIOD_HOURS_KEY = "dfs.datanode.scan.period.hours";
    public static final int DFS_DATANODE_SCAN_PERIOD_HOURS_DEFAULT = 21 * 24; // 3 weeks.
    public static final String DFS_BLOCK_SCANNER_VOLUME_BYTES_PER_SECOND = "dfs.block.scanner.volume.bytes.per.second";
    public static final long DFS_BLOCK_SCANNER_VOLUME_BYTES_PER_SECOND_DEFAULT = 1048576L;
    public static final String DFS_DATANODE_TRANSFERTO_ALLOWED_KEY = "dfs.datanode.transferTo.allowed";
    public static final boolean DFS_DATANODE_TRANSFERTO_ALLOWED_DEFAULT = true;
    public static final String DFS_HEARTBEAT_INTERVAL_KEY = "dfs.heartbeat.interval";
    public static final long DFS_HEARTBEAT_INTERVAL_DEFAULT = 3;
    public static final String DFS_DATANODE_LIFELINE_INTERVAL_SECONDS_KEY = "dfs.datanode.lifeline.interval.seconds";
    public static final String DFS_NAMENODE_PATH_BASED_CACHE_RETRY_INTERVAL_MS = "dfs.namenode.path.based.cache.retry.interval.ms";
    public static final long DFS_NAMENODE_PATH_BASED_CACHE_RETRY_INTERVAL_MS_DEFAULT = 30000L;
    public static final String DFS_NAMENODE_DECOMMISSION_INTERVAL_KEY = "dfs.namenode.decommission.interval";
    public static final int DFS_NAMENODE_DECOMMISSION_INTERVAL_DEFAULT = 30;
    public static final String DFS_NAMENODE_DECOMMISSION_BLOCKS_PER_INTERVAL_KEY = "dfs.namenode.decommission.blocks.per.interval";
    public static final int DFS_NAMENODE_DECOMMISSION_BLOCKS_PER_INTERVAL_DEFAULT = 500000;
    public static final String DFS_NAMENODE_DECOMMISSION_MAX_CONCURRENT_TRACKED_NODES = "dfs.namenode.decommission.max.concurrent.tracked.nodes";
    public static final int DFS_NAMENODE_DECOMMISSION_MAX_CONCURRENT_TRACKED_NODES_DEFAULT = 100;
    public static final String DFS_NAMENODE_HANDLER_COUNT_KEY = "dfs.namenode.handler.count";
    public static final int DFS_NAMENODE_HANDLER_COUNT_DEFAULT = 10;
    public static final String DFS_NAMENODE_LIFELINE_HANDLER_RATIO_KEY = "dfs.namenode.lifeline.handler.ratio";
    public static final float DFS_NAMENODE_LIFELINE_HANDLER_RATIO_DEFAULT = 0.1f;
    public static final String DFS_NAMENODE_LIFELINE_HANDLER_COUNT_KEY = "dfs.namenode.lifeline.handler.count";
    public static final String DFS_NAMENODE_SERVICE_HANDLER_COUNT_KEY = "dfs.namenode.service.handler.count";
    public static final int DFS_NAMENODE_SERVICE_HANDLER_COUNT_DEFAULT = 10;
    public static final String DFS_HTTP_POLICY_KEY = "dfs.http.policy";
    public static final String DFS_HTTP_POLICY_DEFAULT = HttpConfig.Policy.HTTP_ONLY.name();
    public static final String DFS_DEFAULT_CHUNK_VIEW_SIZE_KEY = "dfs.default.chunk.view.size";
    public static final int DFS_DEFAULT_CHUNK_VIEW_SIZE_DEFAULT = 32 * 1024;
    public static final String DFS_DATANODE_HTTPS_ADDRESS_KEY = "dfs.datanode.https.address";
    public static final String DFS_DATANODE_HTTPS_PORT_KEY = "datanode.https.port";
    public static final int DFS_DATANODE_HTTPS_DEFAULT_PORT = 9865;
    public static final String DFS_DATANODE_HTTPS_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_DATANODE_HTTPS_DEFAULT_PORT;
    public static final String DFS_DATANODE_IPC_ADDRESS_KEY = "dfs.datanode.ipc.address";
    public static final int DFS_DATANODE_IPC_DEFAULT_PORT = 9867;
    public static final String DFS_DATANODE_IPC_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_DATANODE_IPC_DEFAULT_PORT;
    public static final String DFS_DATANODE_MIN_SUPPORTED_NAMENODE_VERSION_KEY = "dfs.datanode.min.supported.namenode.version";
    public static final String DFS_DATANODE_MIN_SUPPORTED_NAMENODE_VERSION_DEFAULT = "2.1.0-beta";
    public static final String DFS_NAMENODE_INODE_ATTRIBUTES_PROVIDER_KEY = "dfs.namenode.inode.attributes.provider.class";
    public static final String DFS_NAMENODE_INODE_ATTRIBUTES_PROVIDER_BYPASS_USERS_KEY = "dfs.namenode.inode.attributes.provider.bypass.users";
    public static final String DFS_NAMENODE_INODE_ATTRIBUTES_PROVIDER_BYPASS_USERS_DEFAULT = "";

    public static final String DFS_DATANODE_BP_READY_TIMEOUT_KEY = "dfs.datanode.bp-ready.timeout";
    public static final long DFS_DATANODE_BP_READY_TIMEOUT_DEFAULT = 20;

    public static final String DFS_BLOCK_ACCESS_TOKEN_ENABLE_KEY = "dfs.block.access.token.enable";
    public static final boolean DFS_BLOCK_ACCESS_TOKEN_ENABLE_DEFAULT = false;
    public static final String DFS_BLOCK_ACCESS_KEY_UPDATE_INTERVAL_KEY = "dfs.block.access.key.update.interval";
    public static final long DFS_BLOCK_ACCESS_KEY_UPDATE_INTERVAL_DEFAULT = 600L;
    public static final String DFS_BLOCK_ACCESS_TOKEN_LIFETIME_KEY = "dfs.block.access.token.lifetime";
    public static final long DFS_BLOCK_ACCESS_TOKEN_LIFETIME_DEFAULT = 600L;
    public static final String DFS_BLOCK_ACCESS_TOKEN_PROTOBUF_ENABLE = "dfs.block.access.token.protobuf.enable";
    public static final boolean DFS_BLOCK_ACCESS_TOKEN_PROTOBUF_ENABLE_DEFAULT = false;

    public static final String DFS_BLOCK_REPLICATOR_CLASSNAME_KEY = "dfs.block.replicator.classname";
    public static final Class<BlockPlacementPolicyDefault> DFS_BLOCK_REPLICATOR_CLASSNAME_DEFAULT = BlockPlacementPolicyDefault.class;
    public static final String DFS_REPLICATION_MAX_KEY = "dfs.replication.max";
    public static final int DFS_REPLICATION_MAX_DEFAULT = 512;
    public static final String DFS_BLOCK_PLACEMENT_EC_CLASSNAME_KEY = "dfs.block.placement.ec.classname";
    public static final Class<BlockPlacementPolicyRackFaultTolerant> DFS_BLOCK_PLACEMENT_EC_CLASSNAME_DEFAULT = BlockPlacementPolicyRackFaultTolerant.class;

    public static final String DFS_DF_INTERVAL_KEY = "dfs.df.interval";
    public static final int DFS_DF_INTERVAL_DEFAULT = 60000;
    public static final String DFS_BLOCKREPORT_INCREMENTAL_INTERVAL_MSEC_KEY = "dfs.blockreport.incremental.intervalMsec";
    public static final long DFS_BLOCKREPORT_INCREMENTAL_INTERVAL_MSEC_DEFAULT = 0;
    public static final String DFS_BLOCKREPORT_INTERVAL_MSEC_KEY = "dfs.blockreport.intervalMsec";
    public static final long DFS_BLOCKREPORT_INTERVAL_MSEC_DEFAULT = 6 * 60 * 60 * 1000;
    public static final String DFS_BLOCKREPORT_INITIAL_DELAY_KEY = "dfs.blockreport.initialDelay";
    public static final int DFS_BLOCKREPORT_INITIAL_DELAY_DEFAULT = 0;
    public static final String DFS_BLOCKREPORT_SPLIT_THRESHOLD_KEY = "dfs.blockreport.split.threshold";
    public static final long DFS_BLOCKREPORT_SPLIT_THRESHOLD_DEFAULT = 1000 * 1000;
    public static final String DFS_NAMENODE_MAX_FULL_BLOCK_REPORT_LEASES = "dfs.namenode.max.full.block.report.leases";
    public static final int DFS_NAMENODE_MAX_FULL_BLOCK_REPORT_LEASES_DEFAULT = 6;
    public static final String DFS_NAMENODE_FULL_BLOCK_REPORT_LEASE_LENGTH_MS = "dfs.namenode.full.block.report.lease.length.ms";
    public static final long DFS_NAMENODE_FULL_BLOCK_REPORT_LEASE_LENGTH_MS_DEFAULT = 5L * 60L * 1000L;
    public static final String DFS_CACHEREPORT_INTERVAL_MSEC_KEY = "dfs.cachereport.intervalMsec";
    public static final long DFS_CACHEREPORT_INTERVAL_MSEC_DEFAULT = 10 * 1000;
    public static final String DFS_BLOCK_INVALIDATE_LIMIT_KEY = "dfs.block.invalidate.limit";
    public static final int DFS_BLOCK_INVALIDATE_LIMIT_DEFAULT = 1000;
    public static final String DFS_DEFAULT_MAX_CORRUPT_FILES_RETURNED_KEY = "dfs.corruptfilesreturned.max";
    public static final int DFS_DEFAULT_MAX_CORRUPT_FILES_RETURNED = 500;
    /* Maximum number of blocks to process for initializing replication queues */
    public static final String DFS_BLOCK_MISREPLICATION_PROCESSING_LIMIT = "dfs.block.misreplication.processing.limit";
    public static final int DFS_BLOCK_MISREPLICATION_PROCESSING_LIMIT_DEFAULT = 10000;

    public static final String DFS_DATANODE_OUTLIERS_REPORT_INTERVAL_KEY = "dfs.datanode.outliers.report.interval";
    public static final String DFS_DATANODE_OUTLIERS_REPORT_INTERVAL_DEFAULT = "30m";

    // property for fsimage compression
    public static final String DFS_IMAGE_COMPRESS_KEY = "dfs.image.compress";
    public static final boolean DFS_IMAGE_COMPRESS_DEFAULT = false;
    public static final String DFS_IMAGE_COMPRESSION_CODEC_KEY = "dfs.image.compression.codec";
    public static final String DFS_IMAGE_COMPRESSION_CODEC_DEFAULT = "org.apache.hadoop.io.compress.DefaultCodec";

    public static final String DFS_IMAGE_TRANSFER_RATE_KEY = "dfs.image.transfer.bandwidthPerSec";
    public static final long DFS_IMAGE_TRANSFER_RATE_DEFAULT = 0; //no throttling

    public static final String DFS_IMAGE_TRANSFER_BOOTSTRAP_STANDBY_RATE_KEY = "dfs.image.transfer-bootstrap-standby.bandwidthPerSec";
    public static final long DFS_IMAGE_TRANSFER_BOOTSTRAP_STANDBY_RATE_DEFAULT = 0; //no throttling

    // Image transfer timeout
    public static final String DFS_IMAGE_TRANSFER_TIMEOUT_KEY = "dfs.image.transfer.timeout";
    public static final int DFS_IMAGE_TRANSFER_TIMEOUT_DEFAULT = 60 * 1000;

    // Image transfer chunksize
    public static final String DFS_IMAGE_TRANSFER_CHUNKSIZE_KEY = "dfs.image.transfer.chunksize";
    public static final int DFS_IMAGE_TRANSFER_CHUNKSIZE_DEFAULT = 64 * 1024;

    // Edit Log segment transfer timeout
    public static final String DFS_EDIT_LOG_TRANSFER_TIMEOUT_KEY = "dfs.edit.log.transfer.timeout";
    public static final int DFS_EDIT_LOG_TRANSFER_TIMEOUT_DEFAULT = 30 * 1000;

    // Throttling Edit Log Segment transfer for Journal Sync
    public static final String DFS_EDIT_LOG_TRANSFER_RATE_KEY = "dfs.edit.log.transfer.bandwidthPerSec";
    public static final long DFS_EDIT_LOG_TRANSFER_RATE_DEFAULT = 0; //no throttling

    public static final String DFS_QJM_OPERATIONS_TIMEOUT = "dfs.qjm.operations.timeout";
    public static final long DFS_QJM_OPERATIONS_TIMEOUT_DEFAULT = 60000;

    // Datanode File IO Stats
    public static final String DFS_DATANODE_ENABLE_FILEIO_FAULT_INJECTION_KEY = "dfs.datanode.enable.fileio.fault.injection";
    public static final boolean DFS_DATANODE_ENABLE_FILEIO_FAULT_INJECTION_DEFAULT = false;
    public static final String DFS_DATANODE_FILEIO_PROFILING_SAMPLING_PERCENTAGE_KEY = "dfs.datanode.fileio.profiling.sampling.percentage";
    public static final int DFS_DATANODE_FILEIO_PROFILING_SAMPLING_PERCENTAGE_DEFAULT = 0;

    //Keys with no defaults
    public static final String DFS_DATANODE_PLUGINS_KEY = "dfs.datanode.plugins";
    public static final String DFS_DATANODE_FSDATASET_FACTORY_KEY = "dfs.datanode.fsdataset.factory";
    public static final String DFS_DATANODE_FSDATASET_VOLUME_CHOOSING_POLICY_KEY = "dfs.datanode.fsdataset.volume.choosing.policy";

    public static final String DFS_DATANODE_AVAILABLE_SPACE_VOLUME_CHOOSING_POLICY_BALANCED_SPACE_THRESHOLD_KEY = "dfs.datanode.available-space-volume-choosing-policy.balanced-space-threshold";
    public static final long DFS_DATANODE_AVAILABLE_SPACE_VOLUME_CHOOSING_POLICY_BALANCED_SPACE_THRESHOLD_DEFAULT = 1024L
            * 1024L * 1024L * 10L; // 10 GB
    public static final String DFS_DATANODE_AVAILABLE_SPACE_VOLUME_CHOOSING_POLICY_BALANCED_SPACE_PREFERENCE_FRACTION_KEY = "dfs.datanode.available-space-volume-choosing-policy.balanced-space-preference-fraction";
    public static final float DFS_DATANODE_AVAILABLE_SPACE_VOLUME_CHOOSING_POLICY_BALANCED_SPACE_PREFERENCE_FRACTION_DEFAULT = 0.75f;
    public static final String DFS_DATANODE_SOCKET_WRITE_TIMEOUT_KEY = HdfsClientConfigKeys.DFS_DATANODE_SOCKET_WRITE_TIMEOUT_KEY;
    public static final String DFS_DATANODE_STARTUP_KEY = "dfs.datanode.startup";
    public static final String DFS_NAMENODE_PLUGINS_KEY = "dfs.namenode.plugins";
    public static final String DFS_WEB_UGI_KEY = "dfs.web.ugi";
    public static final String DFS_NAMENODE_STARTUP_KEY = "dfs.namenode.startup";
    public static final String DFS_DATANODE_KEYTAB_FILE_KEY = "dfs.datanode.keytab.file";
    public static final String DFS_DATANODE_KERBEROS_PRINCIPAL_KEY = HdfsClientConfigKeys.DFS_DATANODE_KERBEROS_PRINCIPAL_KEY;
    @Deprecated
    public static final String DFS_DATANODE_USER_NAME_KEY = DFS_DATANODE_KERBEROS_PRINCIPAL_KEY;
    public static final String DFS_DATANODE_SHARED_FILE_DESCRIPTOR_PATHS = "dfs.datanode.shared.file.descriptor.paths";
    public static final String DFS_DATANODE_SHARED_FILE_DESCRIPTOR_PATHS_DEFAULT = "/dev/shm,/tmp";
    public static final String DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS = HdfsClientConfigKeys.DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS;
    public static final int DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT = HdfsClientConfigKeys.DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT;
    public static final String DFS_NAMENODE_KEYTAB_FILE_KEY = "dfs.namenode.keytab.file";
    public static final String DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY = HdfsClientConfigKeys.DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
    @Deprecated
    public static final String DFS_NAMENODE_USER_NAME_KEY = DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY;
    public static final String DFS_NAMENODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY = "dfs.namenode.kerberos.internal.spnego.principal";
    @Deprecated
    public static final String DFS_NAMENODE_INTERNAL_SPNEGO_USER_NAME_KEY = DFS_NAMENODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY;
    public static final String DFS_SECONDARY_NAMENODE_KEYTAB_FILE_KEY = "dfs.secondary.namenode.keytab.file";
    public static final String DFS_SECONDARY_NAMENODE_KERBEROS_PRINCIPAL_KEY = "dfs.secondary.namenode.kerberos.principal";
    @Deprecated
    public static final String DFS_SECONDARY_NAMENODE_USER_NAME_KEY = DFS_SECONDARY_NAMENODE_KERBEROS_PRINCIPAL_KEY;
    public static final String DFS_SECONDARY_NAMENODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY = "dfs.secondary.namenode.kerberos.internal.spnego.principal";
    @Deprecated
    public static final String DFS_SECONDARY_NAMENODE_INTERNAL_SPNEGO_USER_NAME_KEY = DFS_SECONDARY_NAMENODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY;
    public static final String DFS_NAMENODE_NAME_CACHE_THRESHOLD_KEY = "dfs.namenode.name.cache.threshold";
    public static final int DFS_NAMENODE_NAME_CACHE_THRESHOLD_DEFAULT = 10;
    public static final String DFS_NAMENODE_LEGACY_OIV_IMAGE_DIR_KEY = "dfs.namenode.legacy-oiv-image.dir";

    public static final String DFS_NAMESERVICES = HdfsClientConfigKeys.DFS_NAMESERVICES;
    public static final String DFS_NAMESERVICE_ID = HdfsClientConfigKeys.DeprecatedKeys.DFS_NAMESERVICE_ID;
    public static final String DFS_INTERNAL_NAMESERVICES_KEY = "dfs.internal.nameservices";
    public static final String DFS_NAMENODE_RESOURCE_CHECK_INTERVAL_KEY = "dfs.namenode.resource.check.interval";
    public static final int DFS_NAMENODE_RESOURCE_CHECK_INTERVAL_DEFAULT = 5000;
    public static final String DFS_NAMENODE_DU_RESERVED_KEY = "dfs.namenode.resource.du.reserved";
    public static final long DFS_NAMENODE_DU_RESERVED_DEFAULT = 1024 * 1024 * 100; // 100 MB
    public static final String DFS_NAMENODE_CHECKED_VOLUMES_KEY = "dfs.namenode.resource.checked.volumes";
    public static final String DFS_NAMENODE_CHECKED_VOLUMES_MINIMUM_KEY = "dfs.namenode.resource.checked.volumes.minimum";
    public static final int DFS_NAMENODE_CHECKED_VOLUMES_MINIMUM_DEFAULT = 1;
    public static final String DFS_WEB_AUTHENTICATION_SIMPLE_ANONYMOUS_ALLOWED = "dfs.web.authentication.simple.anonymous.allowed";
    public static final String DFS_WEB_AUTHENTICATION_KERBEROS_PRINCIPAL_KEY = "dfs.web.authentication.kerberos.principal";
    public static final String DFS_WEB_AUTHENTICATION_KERBEROS_KEYTAB_KEY = "dfs.web.authentication.kerberos.keytab";
    public static final String DFS_NAMENODE_MAX_OP_SIZE_KEY = "dfs.namenode.max.op.size";
    public static final int DFS_NAMENODE_MAX_OP_SIZE_DEFAULT = 50 * 1024 * 1024;
    public static final String DFS_NAMENODE_AVAILABLE_SPACE_BLOCK_PLACEMENT_POLICY_BALANCED_SPACE_PREFERENCE_FRACTION_KEY = "dfs.namenode.available-space-block-placement-policy.balanced-space-preference-fraction";
    public static final float DFS_NAMENODE_AVAILABLE_SPACE_BLOCK_PLACEMENT_POLICY_BALANCED_SPACE_PREFERENCE_FRACTION_DEFAULT = 0.6f;
    public static final String DFS_NAMENODE_BLOCKPLACEMENTPOLICY_DEFAULT_PREFER_LOCAL_NODE_KEY = "dfs.namenode.block-placement-policy.default.prefer-local-node";
    public static final boolean DFS_NAMENODE_BLOCKPLACEMENTPOLICY_DEFAULT_PREFER_LOCAL_NODE_DEFAULT = true;

    public static final String DFS_BLOCK_LOCAL_PATH_ACCESS_USER_KEY = "dfs.block.local-path-access.user";
    public static final String DFS_DOMAIN_SOCKET_PATH_KEY = HdfsClientConfigKeys.DFS_DOMAIN_SOCKET_PATH_KEY;
    public static final String DFS_DOMAIN_SOCKET_PATH_DEFAULT = HdfsClientConfigKeys.DFS_DOMAIN_SOCKET_PATH_DEFAULT;

    public static final String DFS_STORAGE_POLICY_ENABLED_KEY = "dfs.storage.policy.enabled";
    public static final boolean DFS_STORAGE_POLICY_ENABLED_DEFAULT = true;

    public static final String DFS_QUOTA_BY_STORAGETYPE_ENABLED_KEY = "dfs.quota.by.storage.type.enabled";
    public static final boolean DFS_QUOTA_BY_STORAGETYPE_ENABLED_DEFAULT = true;

    // HA related configuration
    public static final String DFS_HA_NAMENODES_KEY_PREFIX = HdfsClientConfigKeys.DFS_HA_NAMENODES_KEY_PREFIX;
    public static final String DFS_HA_NAMENODE_ID_KEY = "dfs.ha.namenode.id";
    public static final String DFS_HA_STANDBY_CHECKPOINTS_KEY = "dfs.ha.standby.checkpoints";
    public static final boolean DFS_HA_STANDBY_CHECKPOINTS_DEFAULT = true;
    public static final String DFS_HA_LOGROLL_PERIOD_KEY = "dfs.ha.log-roll.period";
    public static final int DFS_HA_LOGROLL_PERIOD_DEFAULT = 2 * 60; // 2m
    public static final String DFS_HA_TAILEDITS_PERIOD_KEY = "dfs.ha.tail-edits.period";
    public static final int DFS_HA_TAILEDITS_PERIOD_DEFAULT = 60; // 1m
    public static final String DFS_HA_TAILEDITS_ALL_NAMESNODES_RETRY_KEY = "dfs.ha.tail-edits.namenode-retries";
    public static final int DFS_HA_TAILEDITS_ALL_NAMESNODES_RETRY_DEFAULT = 3;
    public static final String DFS_HA_TAILEDITS_INPROGRESS_KEY = "dfs.ha.tail-edits.in-progress";
    public static final boolean DFS_HA_TAILEDITS_INPROGRESS_DEFAULT = false;
    public static final String DFS_HA_TAILEDITS_ROLLEDITS_TIMEOUT_KEY = "dfs.ha.tail-edits.rolledits.timeout";
    public static final int DFS_HA_TAILEDITS_ROLLEDITS_TIMEOUT_DEFAULT = 60; // 1m
    public static final String DFS_HA_LOGROLL_RPC_TIMEOUT_KEY = "dfs.ha.log-roll.rpc.timeout";
    public static final int DFS_HA_LOGROLL_RPC_TIMEOUT_DEFAULT = 20000; // 20s
    public static final String DFS_HA_FENCE_METHODS_KEY = "dfs.ha.fencing.methods";
    public static final String DFS_HA_AUTO_FAILOVER_ENABLED_KEY = "dfs.ha.automatic-failover.enabled";
    public static final boolean DFS_HA_AUTO_FAILOVER_ENABLED_DEFAULT = false;
    public static final String DFS_HA_ZKFC_PORT_KEY = "dfs.ha.zkfc.port";
    public static final int DFS_HA_ZKFC_PORT_DEFAULT = 8019;
    public static final String DFS_HA_ZKFC_NN_HTTP_TIMEOUT_KEY = "dfs.ha.zkfc.nn.http.timeout.ms";
    public static final int DFS_HA_ZKFC_NN_HTTP_TIMEOUT_KEY_DEFAULT = 20000;

    // Security-related configs
    public static final String DFS_ENCRYPT_DATA_TRANSFER_KEY = "dfs.encrypt.data.transfer";
    public static final boolean DFS_ENCRYPT_DATA_TRANSFER_DEFAULT = false;
    public static final String DFS_XFRAME_OPTION_ENABLED = "dfs.xframe.enabled";
    public static final boolean DFS_XFRAME_OPTION_ENABLED_DEFAULT = true;

    public static final String DFS_XFRAME_OPTION_VALUE = "dfs.xframe.value";
    public static final String DFS_XFRAME_OPTION_VALUE_DEFAULT = "SAMEORIGIN";

    @Deprecated
    public static final String DFS_ENCRYPT_DATA_TRANSFER_CIPHER_KEY_BITLENGTH_KEY = HdfsClientConfigKeys.DFS_ENCRYPT_DATA_TRANSFER_CIPHER_KEY_BITLENGTH_KEY;
    @Deprecated
    public static final int DFS_ENCRYPT_DATA_TRANSFER_CIPHER_KEY_BITLENGTH_DEFAULT = HdfsClientConfigKeys.DFS_ENCRYPT_DATA_TRANSFER_CIPHER_KEY_BITLENGTH_DEFAULT;
    @Deprecated
    public static final String DFS_ENCRYPT_DATA_TRANSFER_CIPHER_SUITES_KEY = HdfsClientConfigKeys.DFS_ENCRYPT_DATA_TRANSFER_CIPHER_SUITES_KEY;
    public static final String DFS_DATA_ENCRYPTION_ALGORITHM_KEY = "dfs.encrypt.data.transfer.algorithm";
    @Deprecated
    public static final String DFS_TRUSTEDCHANNEL_RESOLVER_CLASS = HdfsClientConfigKeys.DFS_TRUSTEDCHANNEL_RESOLVER_CLASS;
    @Deprecated
    public static final String DFS_DATA_TRANSFER_PROTECTION_KEY = HdfsClientConfigKeys.DFS_DATA_TRANSFER_PROTECTION_KEY;
    @Deprecated
    public static final String DFS_DATA_TRANSFER_PROTECTION_DEFAULT = HdfsClientConfigKeys.DFS_DATA_TRANSFER_PROTECTION_DEFAULT;
    @Deprecated
    public static final String DFS_DATA_TRANSFER_SASL_PROPS_RESOLVER_CLASS_KEY = HdfsClientConfigKeys.DFS_DATA_TRANSFER_SASL_PROPS_RESOLVER_CLASS_KEY;
    public static final int DFS_NAMENODE_LIST_ENCRYPTION_ZONES_NUM_RESPONSES_DEFAULT = 100;
    public static final String DFS_NAMENODE_LIST_ENCRYPTION_ZONES_NUM_RESPONSES = "dfs.namenode.list.encryption.zones.num.responses";
    public static final int DFS_NAMENODE_LIST_REENCRYPTION_STATUS_NUM_RESPONSES_DEFAULT = 100;
    public static final String DFS_NAMENODE_LIST_REENCRYPTION_STATUS_NUM_RESPONSES_KEY = "dfs.namenode.list.reencryption.status.num.responses";
    public static final String DFS_NAMENODE_LIST_OPENFILES_NUM_RESPONSES = "dfs.namenode.list.openfiles.num.responses";
    public static final int DFS_NAMENODE_LIST_OPENFILES_NUM_RESPONSES_DEFAULT = 1000;
    public static final String DFS_NAMENODE_EDEKCACHELOADER_INTERVAL_MS_KEY = "dfs.namenode.edekcacheloader.interval.ms";
    public static final int DFS_NAMENODE_EDEKCACHELOADER_INTERVAL_MS_DEFAULT = 1000;
    public static final String DFS_NAMENODE_EDEKCACHELOADER_INITIAL_DELAY_MS_KEY = "dfs.namenode.edekcacheloader.initial.delay.ms";
    public static final int DFS_NAMENODE_EDEKCACHELOADER_INITIAL_DELAY_MS_DEFAULT = 3000;
    public static final String DFS_NAMENODE_REENCRYPT_SLEEP_INTERVAL_KEY = "dfs.namenode.reencrypt.sleep.interval";
    public static final String DFS_NAMENODE_REENCRYPT_SLEEP_INTERVAL_DEFAULT = "1m";
    public static final String DFS_NAMENODE_REENCRYPT_BATCH_SIZE_KEY = "dfs.namenode.reencrypt.batch.size";
    public static final int DFS_NAMENODE_REENCRYPT_BATCH_SIZE_DEFAULT = 1000;
    public static final String DFS_NAMENODE_REENCRYPT_THROTTLE_LIMIT_HANDLER_RATIO_KEY = "dfs.namenode.reencrypt.throttle.limit.handler.ratio";
    public static final double DFS_NAMENODE_REENCRYPT_THROTTLE_LIMIT_HANDLER_RATIO_DEFAULT = 1.0;
    public static final String DFS_NAMENODE_REENCRYPT_THROTTLE_LIMIT_UPDATER_RATIO_KEY = "dfs.namenode.reencrypt.throttle.limit.updater.ratio";
    public static final double DFS_NAMENODE_REENCRYPT_THROTTLE_LIMIT_UPDATER_RATIO_DEFAULT = 1.0;
    public static final String DFS_NAMENODE_REENCRYPT_EDEK_THREADS_KEY = "dfs.namenode.reencrypt.edek.threads";
    public static final int DFS_NAMENODE_REENCRYPT_EDEK_THREADS_DEFAULT = 10;

    // Journal-node related configs. These are read on the JN side.
    public static final String DFS_JOURNALNODE_EDITS_DIR_KEY = "dfs.journalnode.edits.dir";
    public static final String DFS_JOURNALNODE_EDITS_DIR_DEFAULT = "/tmp/hadoop/dfs/journalnode/";
    public static final String DFS_JOURNALNODE_RPC_ADDRESS_KEY = "dfs.journalnode.rpc-address";
    public static final int DFS_JOURNALNODE_RPC_PORT_DEFAULT = 8485;
    public static final String DFS_JOURNALNODE_RPC_BIND_HOST_KEY = "dfs.journalnode.rpc-bind-host";
    public static final String DFS_JOURNALNODE_RPC_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_JOURNALNODE_RPC_PORT_DEFAULT;

    public static final String DFS_JOURNALNODE_HTTP_ADDRESS_KEY = "dfs.journalnode.http-address";
    public static final int DFS_JOURNALNODE_HTTP_PORT_DEFAULT = 8480;
    public static final String DFS_JOURNALNODE_HTTP_BIND_HOST_KEY = "dfs.journalnode.http-bind-host";
    public static final String DFS_JOURNALNODE_HTTP_ADDRESS_DEFAULT = "0.0.0.0:"
            + DFS_JOURNALNODE_HTTP_PORT_DEFAULT;
    public static final String DFS_JOURNALNODE_HTTPS_ADDRESS_KEY = "dfs.journalnode.https-address";
    public static final int DFS_JOURNALNODE_HTTPS_PORT_DEFAULT = 8481;
    public static final String DFS_JOURNALNODE_HTTPS_BIND_HOST_KEY = "dfs.journalnode.https-bind-host";
    public static final String DFS_JOURNALNODE_HTTPS_ADDRESS_DEFAULT = "0.0.0.0:"
            + DFS_JOURNALNODE_HTTPS_PORT_DEFAULT;

    public static final String DFS_JOURNALNODE_KEYTAB_FILE_KEY = "dfs.journalnode.keytab.file";
    public static final String DFS_JOURNALNODE_KERBEROS_PRINCIPAL_KEY = "dfs.journalnode.kerberos.principal";
    public static final String DFS_JOURNALNODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY = "dfs.journalnode.kerberos.internal.spnego.principal";
    public static final String DFS_JOURNALNODE_ENABLE_SYNC_KEY = "dfs.journalnode.enable.sync";
    public static final boolean DFS_JOURNALNODE_ENABLE_SYNC_DEFAULT = true;
    public static final String DFS_JOURNALNODE_SYNC_INTERVAL_KEY = "dfs.journalnode.sync.interval";
    public static final long DFS_JOURNALNODE_SYNC_INTERVAL_DEFAULT = 2 * 60 * 1000L;

    // Journal-node related configs for the client side.
    public static final String DFS_QJOURNAL_QUEUE_SIZE_LIMIT_KEY = "dfs.qjournal.queued-edits.limit.mb";
    public static final int DFS_QJOURNAL_QUEUE_SIZE_LIMIT_DEFAULT = 10;

    // Quorum-journal timeouts for various operations. Unlikely to need
    // to be tweaked, but configurable just in case.
    public static final String DFS_QJOURNAL_START_SEGMENT_TIMEOUT_KEY = "dfs.qjournal.start-segment.timeout.ms";
    public static final String DFS_QJOURNAL_PREPARE_RECOVERY_TIMEOUT_KEY = "dfs.qjournal.prepare-recovery.timeout.ms";
    public static final String DFS_QJOURNAL_ACCEPT_RECOVERY_TIMEOUT_KEY = "dfs.qjournal.accept-recovery.timeout.ms";
    public static final String DFS_QJOURNAL_FINALIZE_SEGMENT_TIMEOUT_KEY = "dfs.qjournal.finalize-segment.timeout.ms";
    public static final String DFS_QJOURNAL_SELECT_INPUT_STREAMS_TIMEOUT_KEY = "dfs.qjournal.select-input-streams.timeout.ms";
    public static final String DFS_QJOURNAL_GET_JOURNAL_STATE_TIMEOUT_KEY = "dfs.qjournal.get-journal-state.timeout.ms";
    public static final String DFS_QJOURNAL_NEW_EPOCH_TIMEOUT_KEY = "dfs.qjournal.new-epoch.timeout.ms";
    public static final String DFS_QJOURNAL_WRITE_TXNS_TIMEOUT_KEY = "dfs.qjournal.write-txns.timeout.ms";
    public static final String DFS_QJOURNAL_HTTP_OPEN_TIMEOUT_KEY = "dfs.qjournal.http.open.timeout.ms";
    public static final String DFS_QJOURNAL_HTTP_READ_TIMEOUT_KEY = "dfs.qjournal.http.read.timeout.ms";
    public static final int DFS_QJOURNAL_START_SEGMENT_TIMEOUT_DEFAULT = 20000;
    public static final int DFS_QJOURNAL_PREPARE_RECOVERY_TIMEOUT_DEFAULT = 120000;
    public static final int DFS_QJOURNAL_ACCEPT_RECOVERY_TIMEOUT_DEFAULT = 120000;
    public static final int DFS_QJOURNAL_FINALIZE_SEGMENT_TIMEOUT_DEFAULT = 120000;
    public static final int DFS_QJOURNAL_SELECT_INPUT_STREAMS_TIMEOUT_DEFAULT = 20000;
    public static final int DFS_QJOURNAL_GET_JOURNAL_STATE_TIMEOUT_DEFAULT = 120000;
    public static final int DFS_QJOURNAL_NEW_EPOCH_TIMEOUT_DEFAULT = 120000;
    public static final int DFS_QJOURNAL_WRITE_TXNS_TIMEOUT_DEFAULT = 20000;
    public static final int DFS_QJOURNAL_HTTP_OPEN_TIMEOUT_DEFAULT = URLConnectionFactory.DEFAULT_SOCKET_TIMEOUT;
    public static final int DFS_QJOURNAL_HTTP_READ_TIMEOUT_DEFAULT = URLConnectionFactory.DEFAULT_SOCKET_TIMEOUT;

    public static final String DFS_MAX_NUM_BLOCKS_TO_LOG_KEY = "dfs.namenode.max-num-blocks-to-log";
    public static final long DFS_MAX_NUM_BLOCKS_TO_LOG_DEFAULT = 1000l;

    public static final String DFS_NAMENODE_ENABLE_RETRY_CACHE_KEY = "dfs.namenode.enable.retrycache";
    public static final boolean DFS_NAMENODE_ENABLE_RETRY_CACHE_DEFAULT = true;
    public static final String DFS_NAMENODE_RETRY_CACHE_EXPIRYTIME_MILLIS_KEY = "dfs.namenode.retrycache.expirytime.millis";
    public static final long DFS_NAMENODE_RETRY_CACHE_EXPIRYTIME_MILLIS_DEFAULT = 600000; // 10 minutes
    public static final String DFS_NAMENODE_RETRY_CACHE_HEAP_PERCENT_KEY = "dfs.namenode.retrycache.heap.percent";
    public static final float DFS_NAMENODE_RETRY_CACHE_HEAP_PERCENT_DEFAULT = 0.03f;

    // Hidden configuration undocumented in hdfs-site. xml
    // Timeout to wait for block receiver and responder thread to stop
    public static final String DFS_DATANODE_XCEIVER_STOP_TIMEOUT_MILLIS_KEY = "dfs.datanode.xceiver.stop.timeout.millis";
    public static final long DFS_DATANODE_XCEIVER_STOP_TIMEOUT_MILLIS_DEFAULT = 60000;

    // WebHDFS retry policy
    @Deprecated
    public static final String DFS_HTTP_CLIENT_RETRY_POLICY_ENABLED_KEY = HdfsClientConfigKeys.HttpClient.RETRY_POLICY_ENABLED_KEY;
    @Deprecated
    public static final boolean DFS_HTTP_CLIENT_RETRY_POLICY_ENABLED_DEFAULT = HdfsClientConfigKeys.HttpClient.RETRY_POLICY_ENABLED_DEFAULT;
    @Deprecated
    public static final String DFS_HTTP_CLIENT_RETRY_POLICY_SPEC_KEY = HdfsClientConfigKeys.HttpClient.RETRY_POLICY_SPEC_KEY;
    @Deprecated
    public static final String DFS_HTTP_CLIENT_RETRY_POLICY_SPEC_DEFAULT = HdfsClientConfigKeys.HttpClient.RETRY_POLICY_SPEC_DEFAULT;
    @Deprecated
    public static final String DFS_HTTP_CLIENT_FAILOVER_MAX_ATTEMPTS_KEY = HdfsClientConfigKeys.HttpClient.FAILOVER_MAX_ATTEMPTS_KEY;
    @Deprecated
    public static final int DFS_HTTP_CLIENT_FAILOVER_MAX_ATTEMPTS_DEFAULT = HdfsClientConfigKeys.HttpClient.FAILOVER_MAX_ATTEMPTS_DEFAULT;
    @Deprecated
    public static final String DFS_HTTP_CLIENT_RETRY_MAX_ATTEMPTS_KEY = HdfsClientConfigKeys.HttpClient.RETRY_MAX_ATTEMPTS_KEY;
    @Deprecated
    public static final int DFS_HTTP_CLIENT_RETRY_MAX_ATTEMPTS_DEFAULT = HdfsClientConfigKeys.HttpClient.RETRY_MAX_ATTEMPTS_DEFAULT;
    @Deprecated
    public static final String DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_BASE_KEY = HdfsClientConfigKeys.HttpClient.FAILOVER_SLEEPTIME_BASE_KEY;
    @Deprecated
    public static final int DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_BASE_DEFAULT = HdfsClientConfigKeys.HttpClient.FAILOVER_SLEEPTIME_BASE_DEFAULT;
    @Deprecated
    public static final String DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_MAX_KEY = HdfsClientConfigKeys.HttpClient.FAILOVER_SLEEPTIME_MAX_KEY;
    @Deprecated
    public static final int DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_MAX_DEFAULT = HdfsClientConfigKeys.HttpClient.FAILOVER_SLEEPTIME_MAX_DEFAULT;

    // Handling unresolved DN topology mapping
    public static final String DFS_REJECT_UNRESOLVED_DN_TOPOLOGY_MAPPING_KEY = "dfs.namenode.reject-unresolved-dn-topology-mapping";
    public static final boolean DFS_REJECT_UNRESOLVED_DN_TOPOLOGY_MAPPING_DEFAULT = false;

    // Slow io warning log threshold settings for dfsclient and datanode.
    public static final String DFS_DATANODE_SLOW_IO_WARNING_THRESHOLD_KEY = "dfs.datanode.slow.io.warning.threshold.ms";
    public static final long DFS_DATANODE_SLOW_IO_WARNING_THRESHOLD_DEFAULT = 300;

    // Number of parallel threads to load multiple datanode volumes
    public static final String DFS_DATANODE_PARALLEL_VOLUME_LOAD_THREADS_NUM_KEY = "dfs.datanode.parallel.volumes.load.threads.num";
    public static final String DFS_DATANODE_BLOCK_ID_LAYOUT_UPGRADE_THREADS_KEY = "dfs.datanode.block.id.layout.upgrade.threads";
    public static final int DFS_DATANODE_BLOCK_ID_LAYOUT_UPGRADE_THREADS = 12;

    public static final String DFS_NAMENODE_INOTIFY_MAX_EVENTS_PER_RPC_KEY = "dfs.namenode.inotify.max.events.per.rpc";
    public static final int DFS_NAMENODE_INOTIFY_MAX_EVENTS_PER_RPC_DEFAULT = 1000;

    public static final String IGNORE_SECURE_PORTS_FOR_TESTING_KEY = "ignore.secure.ports.for.testing";
    public static final boolean IGNORE_SECURE_PORTS_FOR_TESTING_DEFAULT = false;

    // nntop Configurations
    public static final String NNTOP_ENABLED_KEY = "dfs.namenode.top.enabled";
    public static final boolean NNTOP_ENABLED_DEFAULT = true;
    public static final String NNTOP_BUCKETS_PER_WINDOW_KEY = "dfs.namenode.top.window.num.buckets";
    public static final int NNTOP_BUCKETS_PER_WINDOW_DEFAULT = 10;
    public static final String NNTOP_NUM_USERS_KEY = "dfs.namenode.top.num.users";
    public static final int NNTOP_NUM_USERS_DEFAULT = 10;
    // comma separated list of nntop reporting periods in minutes
    public static final String NNTOP_WINDOWS_MINUTES_KEY = "dfs.namenode.top.windows.minutes";
    public static final String[] NNTOP_WINDOWS_MINUTES_DEFAULT = { "1", "5", "25" };
    public static final String DFS_PIPELINE_ECN_ENABLED = "dfs.pipeline.ecn";
    public static final boolean DFS_PIPELINE_ECN_ENABLED_DEFAULT = false;

    // Key Provider Cache Expiry
    public static final String DFS_DATANODE_BLOCK_PINNING_ENABLED = "dfs.datanode.block-pinning.enabled";
    public static final boolean DFS_DATANODE_BLOCK_PINNING_ENABLED_DEFAULT = false;

    public static final String DFS_DATANODE_TRANSFER_SOCKET_SEND_BUFFER_SIZE_KEY = "dfs.datanode.transfer.socket.send.buffer.size";
    public static final int DFS_DATANODE_TRANSFER_SOCKET_SEND_BUFFER_SIZE_DEFAULT = HdfsConstants.DEFAULT_DATA_SOCKET_SIZE;

    public static final String DFS_DATANODE_TRANSFER_SOCKET_RECV_BUFFER_SIZE_KEY = "dfs.datanode.transfer.socket.recv.buffer.size";
    public static final int DFS_DATANODE_TRANSFER_SOCKET_RECV_BUFFER_SIZE_DEFAULT = HdfsConstants.DEFAULT_DATA_SOCKET_SIZE;

    public static final String DFS_DATA_TRANSFER_SERVER_TCPNODELAY = "dfs.data.transfer.server.tcpnodelay";
    public static final boolean DFS_DATA_TRANSFER_SERVER_TCPNODELAY_DEFAULT = true;

    // Disk Balancer Keys
    public static final String DFS_DISK_BALANCER_ENABLED = "dfs.disk.balancer.enabled";
    public static final boolean DFS_DISK_BALANCER_ENABLED_DEFAULT = true;

    public static final String DFS_DISK_BALANCER_MAX_DISK_THROUGHPUT = "dfs.disk.balancer.max.disk.throughputInMBperSec";
    public static final int DFS_DISK_BALANCER_MAX_DISK_THROUGHPUT_DEFAULT = 10;

    public static final String DFS_DISK_BALANCER_MAX_DISK_ERRORS = "dfs.disk.balancer.max.disk.errors";
    public static final int DFS_DISK_BALANCER_MAX_DISK_ERRORS_DEFAULT = 5;

    public static final String DFS_DISK_BALANCER_PLAN_VALID_INTERVAL = "dfs.disk.balancer.plan.valid.interval";
    public static final String DFS_DISK_BALANCER_PLAN_VALID_INTERVAL_DEFAULT = "1d";

    public static final String DFS_DISK_BALANCER_BLOCK_TOLERANCE = "dfs.disk.balancer.block.tolerance.percent";
    public static final int DFS_DISK_BALANCER_BLOCK_TOLERANCE_DEFAULT = 10;

    public static final String DFS_DISK_BALANCER_PLAN_THRESHOLD = "dfs.disk.balancer.plan.threshold.percent";
    public static final int DFS_DISK_BALANCER_PLAN_THRESHOLD_DEFAULT = 10;

    public static final String HTTPFS_BUFFER_SIZE_KEY = "httpfs.buffer.size";
    public static final int HTTP_BUFFER_SIZE_DEFAULT = 4096;

    public static final String DFS_USE_DFS_NETWORK_TOPOLOGY_KEY = "dfs.use.dfs.network.topology";
    public static final boolean DFS_USE_DFS_NETWORK_TOPOLOGY_DEFAULT = true;

    public static final String DFS_NET_TOPOLOGY_IMPL_KEY = "dfs.net.topology.impl";

    public static final Class<DFSNetworkTopology> DFS_NET_TOPOLOGY_IMPL_DEFAULT = DFSNetworkTopology.class;

    // dfs.client.retry confs are moved to HdfsClientConfigKeys.Retry 
    @Deprecated
    public static final String DFS_CLIENT_RETRY_POLICY_ENABLED_KEY = HdfsClientConfigKeys.Retry.POLICY_ENABLED_KEY;
    @Deprecated
    public static final boolean DFS_CLIENT_RETRY_POLICY_ENABLED_DEFAULT = HdfsClientConfigKeys.Retry.POLICY_ENABLED_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_RETRY_POLICY_SPEC_KEY = HdfsClientConfigKeys.Retry.POLICY_SPEC_KEY;
    @Deprecated
    public static final String DFS_CLIENT_RETRY_POLICY_SPEC_DEFAULT = HdfsClientConfigKeys.Retry.POLICY_SPEC_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_RETRY_TIMES_GET_LAST_BLOCK_LENGTH = HdfsClientConfigKeys.Retry.TIMES_GET_LAST_BLOCK_LENGTH_KEY;
    @Deprecated
    public static final int DFS_CLIENT_RETRY_TIMES_GET_LAST_BLOCK_LENGTH_DEFAULT = HdfsClientConfigKeys.Retry.TIMES_GET_LAST_BLOCK_LENGTH_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_RETRY_INTERVAL_GET_LAST_BLOCK_LENGTH = HdfsClientConfigKeys.Retry.INTERVAL_GET_LAST_BLOCK_LENGTH_KEY;
    @Deprecated
    public static final int DFS_CLIENT_RETRY_INTERVAL_GET_LAST_BLOCK_LENGTH_DEFAULT = HdfsClientConfigKeys.Retry.INTERVAL_GET_LAST_BLOCK_LENGTH_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_RETRY_MAX_ATTEMPTS_KEY = HdfsClientConfigKeys.Retry.MAX_ATTEMPTS_KEY;
    @Deprecated
    public static final int DFS_CLIENT_RETRY_MAX_ATTEMPTS_DEFAULT = HdfsClientConfigKeys.Retry.MAX_ATTEMPTS_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_RETRY_WINDOW_BASE = HdfsClientConfigKeys.Retry.WINDOW_BASE_KEY;
    @Deprecated
    public static final int DFS_CLIENT_RETRY_WINDOW_BASE_DEFAULT = HdfsClientConfigKeys.Retry.WINDOW_BASE_DEFAULT;

    // dfs.client.failover confs are moved to HdfsClientConfigKeys.Failover 
    @Deprecated
    public static final String DFS_CLIENT_FAILOVER_PROXY_PROVIDER_KEY_PREFIX = HdfsClientConfigKeys.Failover.PROXY_PROVIDER_KEY_PREFIX;
    @Deprecated
    public static final String DFS_CLIENT_FAILOVER_MAX_ATTEMPTS_KEY = HdfsClientConfigKeys.Failover.MAX_ATTEMPTS_KEY;
    @Deprecated
    public static final int DFS_CLIENT_FAILOVER_MAX_ATTEMPTS_DEFAULT = HdfsClientConfigKeys.Failover.MAX_ATTEMPTS_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_FAILOVER_SLEEPTIME_BASE_KEY = HdfsClientConfigKeys.Failover.SLEEPTIME_BASE_KEY;
    @Deprecated
    public static final int DFS_CLIENT_FAILOVER_SLEEPTIME_BASE_DEFAULT = HdfsClientConfigKeys.Failover.SLEEPTIME_BASE_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_FAILOVER_SLEEPTIME_MAX_KEY = HdfsClientConfigKeys.Failover.SLEEPTIME_MAX_KEY;
    @Deprecated
    public static final int DFS_CLIENT_FAILOVER_SLEEPTIME_MAX_DEFAULT = HdfsClientConfigKeys.Failover.SLEEPTIME_MAX_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_FAILOVER_CONNECTION_RETRIES_KEY = HdfsClientConfigKeys.Failover.CONNECTION_RETRIES_KEY;
    @Deprecated
    public static final int DFS_CLIENT_FAILOVER_CONNECTION_RETRIES_DEFAULT = HdfsClientConfigKeys.Failover.CONNECTION_RETRIES_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_FAILOVER_CONNECTION_RETRIES_ON_SOCKET_TIMEOUTS_KEY = HdfsClientConfigKeys.Failover.CONNECTION_RETRIES_ON_SOCKET_TIMEOUTS_KEY;
    @Deprecated
    public static final int DFS_CLIENT_FAILOVER_CONNECTION_RETRIES_ON_SOCKET_TIMEOUTS_DEFAULT = HdfsClientConfigKeys.Failover.CONNECTION_RETRIES_ON_SOCKET_TIMEOUTS_DEFAULT;

    // dfs.client.write confs are moved to HdfsClientConfigKeys.Write 
    @Deprecated
    public static final String DFS_CLIENT_WRITE_MAX_PACKETS_IN_FLIGHT_KEY = HdfsClientConfigKeys.Write.MAX_PACKETS_IN_FLIGHT_KEY;
    @Deprecated
    public static final int DFS_CLIENT_WRITE_MAX_PACKETS_IN_FLIGHT_DEFAULT = HdfsClientConfigKeys.Write.MAX_PACKETS_IN_FLIGHT_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_EXCLUDE_NODES_CACHE_EXPIRY_INTERVAL = HdfsClientConfigKeys.Write.EXCLUDE_NODES_CACHE_EXPIRY_INTERVAL_KEY;
    @Deprecated
    public static final long DFS_CLIENT_WRITE_EXCLUDE_NODES_CACHE_EXPIRY_INTERVAL_DEFAULT = HdfsClientConfigKeys.Write.EXCLUDE_NODES_CACHE_EXPIRY_INTERVAL_DEFAULT; // 10 minutes, in ms
    @Deprecated
    public static final String DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_ENABLED_KEY = HdfsClientConfigKeys.Write.ByteArrayManager.ENABLED_KEY;
    @Deprecated
    public static final boolean DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_ENABLED_DEFAULT = HdfsClientConfigKeys.Write.ByteArrayManager.ENABLED_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_COUNT_THRESHOLD_KEY = HdfsClientConfigKeys.Write.ByteArrayManager.COUNT_THRESHOLD_KEY;
    @Deprecated
    public static final int DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_COUNT_THRESHOLD_DEFAULT = HdfsClientConfigKeys.Write.ByteArrayManager.COUNT_THRESHOLD_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_COUNT_LIMIT_KEY = HdfsClientConfigKeys.Write.ByteArrayManager.COUNT_LIMIT_KEY;
    @Deprecated
    public static final int DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_COUNT_LIMIT_DEFAULT = HdfsClientConfigKeys.Write.ByteArrayManager.COUNT_LIMIT_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_COUNT_RESET_TIME_PERIOD_MS_KEY = HdfsClientConfigKeys.Write.ByteArrayManager.COUNT_RESET_TIME_PERIOD_MS_KEY;
    @Deprecated
    public static final long DFS_CLIENT_WRITE_BYTE_ARRAY_MANAGER_COUNT_RESET_TIME_PERIOD_MS_DEFAULT = HdfsClientConfigKeys.Write.ByteArrayManager.COUNT_RESET_TIME_PERIOD_MS_DEFAULT;

    // dfs.client.block.write confs are moved to HdfsClientConfigKeys.BlockWrite 
    @Deprecated
    public static final String DFS_CLIENT_BLOCK_WRITE_RETRIES_KEY = HdfsClientConfigKeys.BlockWrite.RETRIES_KEY;
    @Deprecated
    public static final int DFS_CLIENT_BLOCK_WRITE_RETRIES_DEFAULT = HdfsClientConfigKeys.BlockWrite.RETRIES_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_BLOCK_WRITE_LOCATEFOLLOWINGBLOCK_RETRIES_KEY = HdfsClientConfigKeys.BlockWrite.LOCATEFOLLOWINGBLOCK_RETRIES_KEY;
    @Deprecated
    public static final int DFS_CLIENT_BLOCK_WRITE_LOCATEFOLLOWINGBLOCK_RETRIES_DEFAULT = HdfsClientConfigKeys.BlockWrite.LOCATEFOLLOWINGBLOCK_RETRIES_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_BLOCK_WRITE_LOCATEFOLLOWINGBLOCK_INITIAL_DELAY_KEY = HdfsClientConfigKeys.BlockWrite.LOCATEFOLLOWINGBLOCK_INITIAL_DELAY_MS_KEY;
    @Deprecated
    public static final int DFS_CLIENT_BLOCK_WRITE_LOCATEFOLLOWINGBLOCK_INITIAL_DELAY_DEFAULT = HdfsClientConfigKeys.BlockWrite.LOCATEFOLLOWINGBLOCK_INITIAL_DELAY_MS_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_ENABLE_KEY = HdfsClientConfigKeys.BlockWrite.ReplaceDatanodeOnFailure.ENABLE_KEY;
    @Deprecated
    public static final boolean DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_ENABLE_DEFAULT = HdfsClientConfigKeys.BlockWrite.ReplaceDatanodeOnFailure.ENABLE_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_POLICY_KEY = HdfsClientConfigKeys.BlockWrite.ReplaceDatanodeOnFailure.POLICY_KEY;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_POLICY_DEFAULT = HdfsClientConfigKeys.BlockWrite.ReplaceDatanodeOnFailure.POLICY_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_BEST_EFFORT_KEY = HdfsClientConfigKeys.BlockWrite.ReplaceDatanodeOnFailure.BEST_EFFORT_KEY;
    @Deprecated
    public static final boolean DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_BEST_EFFORT_DEFAULT = HdfsClientConfigKeys.BlockWrite.ReplaceDatanodeOnFailure.BEST_EFFORT_DEFAULT;

    // dfs.client.read confs are moved to HdfsClientConfigKeys.Read 
    @Deprecated
    public static final String DFS_CLIENT_READ_PREFETCH_SIZE_KEY = HdfsClientConfigKeys.Read.PREFETCH_SIZE_KEY;
    @Deprecated
    public static final String DFS_CLIENT_READ_SHORTCIRCUIT_KEY = HdfsClientConfigKeys.Read.ShortCircuit.KEY;
    @Deprecated
    public static final boolean DFS_CLIENT_READ_SHORTCIRCUIT_DEFAULT = HdfsClientConfigKeys.Read.ShortCircuit.DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_READ_SHORTCIRCUIT_SKIP_CHECKSUM_KEY = HdfsClientConfigKeys.Read.ShortCircuit.SKIP_CHECKSUM_KEY;
    @Deprecated
    public static final boolean DFS_CLIENT_READ_SHORTCIRCUIT_SKIP_CHECKSUM_DEFAULT = HdfsClientConfigKeys.Read.ShortCircuit.SKIP_CHECKSUM_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_READ_SHORTCIRCUIT_BUFFER_SIZE_KEY = HdfsClientConfigKeys.Read.ShortCircuit.BUFFER_SIZE_KEY;
    @Deprecated
    public static final int DFS_CLIENT_READ_SHORTCIRCUIT_BUFFER_SIZE_DEFAULT = HdfsClientConfigKeys.Read.ShortCircuit.BUFFER_SIZE_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_SIZE_KEY = HdfsClientConfigKeys.Read.ShortCircuit.STREAMS_CACHE_SIZE_KEY;
    @Deprecated
    public static final int DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_SIZE_DEFAULT = HdfsClientConfigKeys.Read.ShortCircuit.STREAMS_CACHE_SIZE_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_EXPIRY_MS_KEY = HdfsClientConfigKeys.Read.ShortCircuit.STREAMS_CACHE_EXPIRY_MS_KEY;
    @Deprecated
    public static final long DFS_CLIENT_READ_SHORTCIRCUIT_STREAMS_CACHE_EXPIRY_MS_DEFAULT = HdfsClientConfigKeys.Read.ShortCircuit.STREAMS_CACHE_EXPIRY_MS_DEFAULT;

    // dfs.client.mmap confs are moved to HdfsClientConfigKeys.Mmap 
    @Deprecated
    public static final String DFS_CLIENT_MMAP_ENABLED = HdfsClientConfigKeys.Mmap.ENABLED_KEY;
    @Deprecated
    public static final boolean DFS_CLIENT_MMAP_ENABLED_DEFAULT = HdfsClientConfigKeys.Mmap.ENABLED_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_MMAP_CACHE_SIZE = HdfsClientConfigKeys.Mmap.CACHE_SIZE_KEY;
    @Deprecated
    public static final int DFS_CLIENT_MMAP_CACHE_SIZE_DEFAULT = HdfsClientConfigKeys.Mmap.CACHE_SIZE_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_MMAP_CACHE_TIMEOUT_MS = HdfsClientConfigKeys.Mmap.CACHE_TIMEOUT_MS_KEY;
    @Deprecated
    public static final long DFS_CLIENT_MMAP_CACHE_TIMEOUT_MS_DEFAULT = HdfsClientConfigKeys.Mmap.CACHE_TIMEOUT_MS_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_MMAP_RETRY_TIMEOUT_MS = HdfsClientConfigKeys.Mmap.RETRY_TIMEOUT_MS_KEY;
    @Deprecated
    public static final long DFS_CLIENT_MMAP_RETRY_TIMEOUT_MS_DEFAULT = HdfsClientConfigKeys.Mmap.RETRY_TIMEOUT_MS_DEFAULT;

    // dfs.client.short.circuit confs are moved to HdfsClientConfigKeys.ShortCircuit 
    @Deprecated
    public static final String DFS_CLIENT_SHORT_CIRCUIT_REPLICA_STALE_THRESHOLD_MS = HdfsClientConfigKeys.ShortCircuit.REPLICA_STALE_THRESHOLD_MS_KEY;
    @Deprecated
    public static final long DFS_CLIENT_SHORT_CIRCUIT_REPLICA_STALE_THRESHOLD_MS_DEFAULT = HdfsClientConfigKeys.ShortCircuit.REPLICA_STALE_THRESHOLD_MS_DEFAULT;

    // dfs.client.hedged.read confs are moved to HdfsClientConfigKeys.HedgedRead 
    @Deprecated
    public static final String DFS_DFSCLIENT_HEDGED_READ_THRESHOLD_MILLIS = HdfsClientConfigKeys.HedgedRead.THRESHOLD_MILLIS_KEY;
    @Deprecated
    public static final long DEFAULT_DFSCLIENT_HEDGED_READ_THRESHOLD_MILLIS = HdfsClientConfigKeys.HedgedRead.THRESHOLD_MILLIS_DEFAULT;
    @Deprecated
    public static final String DFS_DFSCLIENT_HEDGED_READ_THREADPOOL_SIZE = HdfsClientConfigKeys.HedgedRead.THREADPOOL_SIZE_KEY;
    @Deprecated
    public static final int DEFAULT_DFSCLIENT_HEDGED_READ_THREADPOOL_SIZE = HdfsClientConfigKeys.HedgedRead.THREADPOOL_SIZE_DEFAULT;

    @Deprecated
    public static final String DFS_CLIENT_SOCKET_TIMEOUT_KEY = HdfsClientConfigKeys.DFS_CLIENT_SOCKET_TIMEOUT_KEY;
    @Deprecated
    public static final String DFS_CLIENT_SOCKET_CACHE_CAPACITY_KEY = HdfsClientConfigKeys.DFS_CLIENT_SOCKET_CACHE_CAPACITY_KEY;
    @Deprecated
    public static final int DFS_CLIENT_SOCKET_CACHE_CAPACITY_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_SOCKET_CACHE_CAPACITY_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_SOCKET_CACHE_EXPIRY_MSEC_KEY = HdfsClientConfigKeys.DFS_CLIENT_SOCKET_CACHE_EXPIRY_MSEC_KEY;
    @Deprecated
    public static final long DFS_CLIENT_SOCKET_CACHE_EXPIRY_MSEC_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_SOCKET_CACHE_EXPIRY_MSEC_DEFAULT;

    @Deprecated
    public static final String DFS_CLIENT_USE_DN_HOSTNAME = HdfsClientConfigKeys.DFS_CLIENT_USE_DN_HOSTNAME;
    @Deprecated
    public static final boolean DFS_CLIENT_USE_DN_HOSTNAME_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_USE_DN_HOSTNAME_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_CACHE_DROP_BEHIND_WRITES = HdfsClientConfigKeys.DFS_CLIENT_CACHE_DROP_BEHIND_WRITES;
    @Deprecated
    public static final String DFS_CLIENT_CACHE_DROP_BEHIND_READS = HdfsClientConfigKeys.DFS_CLIENT_CACHE_DROP_BEHIND_READS;
    @Deprecated
    public static final String DFS_CLIENT_CACHE_READAHEAD = HdfsClientConfigKeys.DFS_CLIENT_CACHE_READAHEAD;
    @Deprecated
    public static final String DFS_CLIENT_CACHED_CONN_RETRY_KEY = HdfsClientConfigKeys.DFS_CLIENT_CACHED_CONN_RETRY_KEY;
    @Deprecated
    public static final int DFS_CLIENT_CACHED_CONN_RETRY_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_CACHED_CONN_RETRY_DEFAULT;

    @Deprecated
    public static final String DFS_CLIENT_CONTEXT = HdfsClientConfigKeys.DFS_CLIENT_CONTEXT;
    @Deprecated
    public static final String DFS_CLIENT_CONTEXT_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_CONTEXT_DEFAULT;

    @Deprecated
    public static final String DFS_CLIENT_DATANODE_RESTART_TIMEOUT_KEY = HdfsClientConfigKeys.DFS_CLIENT_DATANODE_RESTART_TIMEOUT_KEY;
    @Deprecated
    public static final long DFS_CLIENT_DATANODE_RESTART_TIMEOUT_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_DATANODE_RESTART_TIMEOUT_DEFAULT;

    public static final String DFS_CLIENT_HTTPS_KEYSTORE_RESOURCE_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_CLIENT_HTTPS_KEYSTORE_RESOURCE_KEY;
    public static final String DFS_CLIENT_HTTPS_KEYSTORE_RESOURCE_DEFAULT = "ssl-client.xml";
    public static final String DFS_CLIENT_HTTPS_NEED_AUTH_KEY = HdfsClientConfigKeys.DeprecatedKeys.DFS_CLIENT_HTTPS_NEED_AUTH_KEY;
    public static final boolean DFS_CLIENT_HTTPS_NEED_AUTH_DEFAULT = false;

    // Much code in hdfs is not yet updated to use these keys.
    // the initial delay (unit is ms) for locateFollowingBlock, the delay time will increase exponentially(double) for each retry.
    @Deprecated
    public static final String DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_KEY = HdfsClientConfigKeys.DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_KEY;
    @Deprecated
    public static final int DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_DEFAULT;

    @Deprecated
    public static final String DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL = HdfsClientConfigKeys.DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL;
    @Deprecated
    public static final boolean DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL_DEFAULT;
    @Deprecated
    public static final String DFS_CLIENT_LOCAL_INTERFACES = HdfsClientConfigKeys.DFS_CLIENT_LOCAL_INTERFACES;

    @Deprecated
    public static final String DFS_CLIENT_DOMAIN_SOCKET_DATA_TRAFFIC = HdfsClientConfigKeys.DFS_CLIENT_DOMAIN_SOCKET_DATA_TRAFFIC;
    @Deprecated
    public static final boolean DFS_CLIENT_DOMAIN_SOCKET_DATA_TRAFFIC_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_DOMAIN_SOCKET_DATA_TRAFFIC_DEFAULT;

    @Deprecated
    public static final String DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY = HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY;
    @Deprecated
    public static final int DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_DEFAULT;

    @Deprecated
    public static final String DFS_CLIENT_KEY_PROVIDER_CACHE_EXPIRY_MS = HdfsClientConfigKeys.DFS_CLIENT_KEY_PROVIDER_CACHE_EXPIRY_MS;
    @Deprecated
    public static final long DFS_CLIENT_KEY_PROVIDER_CACHE_EXPIRY_DEFAULT = HdfsClientConfigKeys.DFS_CLIENT_KEY_PROVIDER_CACHE_EXPIRY_DEFAULT;

}