/**
 * 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 java.util.concurrent.TimeUnit;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault;
import org.apache.hadoop.hdfs.server.namenode.XAttrStorage;
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 {
  //db storage
  public static final String DFS_STORAGE_DRIVER_JAR_FILE = "dfs.storage.driver.jarFile";
  public static final String DFS_STORAGE_DRIVER_JAR_FILE_DEFAULT = "";
  public static final String DFS_STORAGE_DRIVER_CLASS = "dfs.storage.driver.class";
  public static final String DFS_STORAGE_DRIVER_CLASS_DEFAULT = "io.hops.metadata.ndb.NdbStorageFactory";
  public static final String DFS_STORAGE_DRIVER_CONFIG_FILE = "dfs.storage.driver.configfile";
  public static final String DFS_STORAGE_DRIVER_CONFIG_FILE_DEFAULT = "ndb-config.properties";

  //quota
  public static final String DFS_NAMENODE_QUOTA_ENABLED_KEY = "dfs.namenode.quota.enabled";
  public static final boolean DFS_NAMENODE_QUOTA_ENABLED_DEFAULT = true;
  public static final String DFS_NAMENODE_QUOTA_UPDATE_INTERVAL_KEY = "dfs.namenode.quota.update.interval";
  public static final int DFS_NAMENODE_QUOTA_UPDATE_INTERVAL_DEFAULT = 1000;
  public static final String DFS_NAMENODE_QUOTA_UPDATE_LIMIT_KEY = "dfs.namenode.quota.update.limit";
  public static final int DFS_NAMENODE_QUOTA_UPDATE_LIMIT_DEFAULT = 5000;
  public static final String DFS_NAMENODE_QUOTA_UPDATE_ID_BATCH_SIZE = "dfs.namenode.quota.update.id.batchsize";
  public static final int DFS_NAMENODE_QUOTA_UPDATE_ID_BATCH_SIZ_DEFAULT = 100000;
  public static final String DFS_NAMENODE_QUOTA_UPDATE_ID_UPDATE_THRESHOLD = "dfs.namenode.quota.update.updateThreshold";
  public static final float DFS_NAMENODE_QUOTA_UPDATE_ID_UPDATE_THRESHOLD_DEFAULT = (float) 0.5;

  //NN batches
  public static final String DFS_NAMENODE_INODEID_BATCH_SIZE = "dfs.namenode.inodeid.batchsize";
  public static final int DFS_NAMENODE_INODEID_BATCH_SIZE_DEFAULT = 1000;
  public static final String DFS_NAMENODE_BLOCKID_BATCH_SIZE = "dfs.namenode.blockid.batchsize";
  public static final int DFS_NAMENODE_BLOCKID_BATCH_SIZE_DEFAULT = 1000;
  public static final String DFS_NAMENODE_INODEID_UPDATE_THRESHOLD = "dfs.namenode.inodeid.updateThreshold";
  public static final float DFS_NAMENODE_INODEID_UPDATE_THRESHOLD_DEFAULT = (float) 0.5;
  public static final String DFS_NAMENODE_BLOCKID_UPDATE_THRESHOLD = "dfs.namenode.blockid.updateThreshold";
  public static final float DFS_NAMENODE_BLOCKID_UPDATE_THRESHOLD_DEFAULT = (float) 0.5;  
  public static final String DFS_NAMENODE_CACHE_DIRECTIVE_ID_BATCH_SIZE = "dfs.namenode.cache.directive.id.batchsize";
  public static final int DFS_NAMENODE_CACHE_DIRECTIVE_ID_BATCH_SIZE_DEFAULT = 100000;
  public static final String DFS_NAMENODE_CACHE_DIRECTIVE_ID_UPDATE_THRESHOLD = "dfs.namenode.cache.directive.updateThreshold";
  public static final float DFS_NAMENODE_CACHE_DIRECTIVE_ID_UPDATE_THRESHOLD_DEFAULT = (float) 0.5;
  public static final String DFS_NAMENODE_IDSMONITOR_CHECK_INTERVAL_IN_MS = "dfs.namenode.id.updateThreshold";
  public static final int DFS_NAMENODE_IDSMONITOR_CHECK_INTERVAL_IN_MS_DEFAULT = 1000;
  public static final String DFS_NAMENODE_SLICER_BATCH_SIZE = "dfs.namenode.slicer.batchsize";
  public static final int DFS_NAMENODE_SLICER_BATCH_SIZE_DEFAULT = 500;
  public static final String DFS_NAMENODE_PROCESS_MISREPLICATED_NO_OF_BATCHS = "dfs.namenode.misreplicated.noofbatches";
  public static final int DFS_NAMENODE_PROCESS_MISREPLICATED_NO_OF_BATCHS_DEFAULT = 100;
  public static final String DFS_NAMENODE_SLICER_NB_OF_THREADS = "dfs.namenode.slicer.nbofthreads";
  public static final int DFS_NAMENODE_SLICER_NB_OF_THREADS_DEFAULT = 20;
  public static final String DFS_TRANSACTION_STATS_ENABLED = "dfs.transaction.stats.enabled";
  public static final boolean DFS_TRANSACTION_STATS_ENABLED_DEFAULT = false;
  public static final String DFS_TRANSACTION_STATS_DETAILED_ENABLED = "dfs.transaction.stats.detailed.enabled";
  public static final boolean DFS_TRANSACTION_STATS_DETAILED_ENABLED_DEFAULT = false;
  public static final String DFS_TRANSACTION_STATS_DIR = "dfs.transaction.stats.dir";
  public static final String DFS_TRANSACTION_STATS_DIR_DEFAULT = "/tmp/hopsstats";
  public static final String DFS_TRANSACTION_STATS_WRITER_ROUND = "dfs.transaction.stats.writerround";
  public static final int DFS_TRANSACTION_STATS_WRITER_ROUND_DEFAULT = 120;
  public static final String  DFS_DIR_DELETE_BATCH_SIZE= "dfs.dir.delete.batch.size";
  public static final int DFS_DIR_DELETE_BATCH_SIZE_DEFAULT = 50;

  /*for client failover api*/
  // format {ip:port, ip:port, ip:port} comma separated
  public static final String DFS_NAMENODES_RPC_ADDRESS_KEY = "dfs.namenodes.rpc.addresses";
  public static final String DFS_NAMENODES_RPC_ADDRESS_DEFAULT = "";

  // format {ip:port, ip:port, ip:port} comma separated
  public static final String DFS_NAMENODES_SERVICE_RPC_ADDRESS_KEY = "dfs.namenodes.servicerpc.addresses";

  public static final String DFS_NAME_SPACE_ID_KEY = "dfs.name.space.id";
  public static final int DFS_NAME_SPACE_ID_DEFAULT = 911; // :)
  
  public static final String DFS_NAMENODE_TX_RETRY_COUNT_KEY = "dfs.namenode.tx.retry.count";
  public static final int DFS_NAMENODE_TX_RETRY_COUNT_DEFAULT = 5;

  public static final String DFS_NAMENODE_TX_INITIAL_WAIT_TIME_BEFORE_RETRY_KEY = "dfs.namenode.tx.initial.wait.time.before.retry";
  public static final int DFS_NAMENODE_TX_INITIAL_WAIT_TIME_BEFORE_RETRY_DEFAULT = 2000;

  public static final String DFS_SET_PARTITION_KEY_ENABLED = "dfs.ndb.setpartitionkey.enabled";
  public static final boolean DFS_SET_PARTITION_KEY_ENABLED_DEFAULT = true;

  public static final String  DFS_SET_RANDOM_PARTITION_KEY_ENABLED = "dfs.ndb.setrandompartitionkey.enabled";
  public static final boolean  DFS_SET_RANDOM_PARTITION_KEY_ENABLED_DEFAULT = true;

  public static final String DFS_RESOLVING_CACHE_ENABLED = "dfs" + ".resolvingcache.enabled";
  public static final boolean DFS_RESOLVING_CACHE_ENABLED_DEFAULT = true;
  
  public static final String DFS_RESOLVING_CACHE_TYPE = "dfs.resolvingcache.type";

  //INode, Path, InMemory, Optimal
  public static final String DFS_RESOLVING_CACHE_TYPE_DEFAULT = "InMemory";

  public static final String DFS_INMEMORY_CACHE_MAX_SIZE = "dfs.resolvingcache.inmemory.maxsize";
  public static final int DFS_INMEMORY_CACHE_MAX_SIZE_DEFAULT = 100000;
  
  public static final String DFS_NDC_ENABLED_KEY = "dfs.ndc.enable";
  public static final boolean DFS_NDC_ENABLED_DEFAULT = false;

  public static final String DFS_SUBTREE_EXECUTOR_LIMIT_KEY = "dfs.namenode.subtree-executor-limit";
  public static final int DFS_SUBTREE_EXECUTOR_LIMIT_DEFAULT = 80;

  public static final String DFS_SUBTREE_QUIESCE_LOCK_BATCH_SIZE_KEY = "dfs.subtree.quiesce.lock.batch.size.key";
  public static final int DFS_SUBTREE_QUIESCE_LOCK_BATCH_SIZE_DEFAULT = 1000;

  public static final String DFS_SUBTREE_CLEAN_FAILED_OPS_LOCKS_DELAY_KEY = "dfs.subtree.clean.failed.ops.locks.delay";
  public static final long DFS_SUBTREE_CLEAN_FAILED_OPS_LOCKS_DELAY_DEFAULT = 10*1000*60; //Reclaim locks after 10 mins

  public static final String DFS_SUBTREE_CLEAN_SLOW_OPS_LOCKS_DELAY_KEY = "dfs.subtree.clean.failed.ops.locks.delay";
  public static final long DFS_SUBTREE_CLEAN_SLOW_OPS_LOCKS_DELAY_DEFAULT = 15*1000*60; //Reclaim locks after 15 mins

  public static final String DFS_SUBTREE_HIERARCHICAL_LOCKING_KEY = "dfs.namenode.subtree.hierarchical.locking";
  public static final boolean DFS_SUBTREE_HIERARCHICAL_LOCKING_KEY_DEFAULT = true;

  public static final String ERASURE_CODING_CODECS_KEY = "dfs.erasure_coding.codecs.json";
  public static final String ERASURE_CODING_ENABLED_KEY = "dfs.erasure_coding.enabled";
  public static final boolean DEFAULT_ERASURE_CODING_ENABLED_KEY = false;
  public static final String PARITY_FOLDER = "dfs.erasure_coding.parity_folder";
  public static final String DEFAULT_PARITY_FOLDER = "/parity";
  public static final String ENCODING_MANAGER_CLASSNAME_KEY = "dfs.erasure_coding.encoding_manager";
  public static final String DEFAULT_ENCODING_MANAGER_CLASSNAME = "io.hops.erasure_coding.MapReduceEncodingManager";
  public static final String BLOCK_REPAIR_MANAGER_CLASSNAME_KEY = "dfs.erasure_coding.block_rapair_manager";
  public static final String DEFAULT_BLOCK_REPAIR_MANAGER_CLASSNAME = "io.hops.erasure_coding.MapReduceBlockRepairManager";
  public static final String RECHECK_INTERVAL_KEY = "dfs.erasure_coding.recheck_interval";
  public static final int DEFAULT_RECHECK_INTERVAL = 5 * 60 * 1000;
  public static final String ACTIVE_ENCODING_LIMIT_KEY = "dfs.erasure_coding.active_encoding_limit";
  public static final int DEFAULT_ACTIVE_ENCODING_LIMIT = 10;
  public static final String ACTIVE_REPAIR_LIMIT_KEY = "dfs.erasure_coding.active_repair_limit";
  public static final int DEFAULT_ACTIVE_REPAIR_LIMIT = 10;
  public static final String REPAIR_DELAY_KEY = "dfs.erasure_coding.repair_delay";
  public static final int DEFAULT_REPAIR_DELAY_KEY = 30 * 60 * 1000;
  public static final String ACTIVE_PARITY_REPAIR_LIMIT_KEY = "dfs.erasure_coding.active_parity_repair_limit";
  public static final int DEFAULT_ACTIVE_PARITY_REPAIR_LIMIT = 10;
  public static final String PARITY_REPAIR_DELAY_KEY = "dfs.erasure_coding.parity_repair_delay";
  public static final int DEFAULT_PARITY_REPAIR_DELAY = 30 * 60 * 1000;
  public static final String DELETION_LIMIT_KEY = "dfs.erasure_coding.deletion_limit";
  public static final int DEFAULT_DELETION_LIMIT = 100;

  public static final String DFS_BR_LB_MAX_CONCURRENT_BR_PER_NN = "dfs.block.report.load.balancer.max.concurrent.block.reports.per.nn";
  public static final long DFS_BR_LB_MAX_CONCURRENT_BR_PER_NN_DEFAULT = 1;

  //read the new value from the data base after every minute
  public static final String DFS_BR_LB_DB_VAR_UPDATE_THRESHOLD = "dfs.block.report.load.balancing.db.var.update.threashold";
  public static final long DFS_BR_LB_DB_VAR_UPDATE_THRESHOLD_DEFAULT = 60*1000;

  //a block report is considered dead if it has not finished processing in one hr
  public static final String DFS_BR_LB_MAX_BR_PROCESSING_TIME = "dfs.block.report.load.balancing.max.block.report.processing.time";
  public static final long DFS_BR_LB_MAX_BR_PROCESSING_TIME_DEFAULT = 60*60*1000;

  public static final String DFS_FORCE_CLIENT_TO_WRITE_SMALL_FILES_TO_DISK_KEY = "dfs.force.client.to.write.small.files.to.disk.key";
  public static final boolean DFS_FORCE_CLIENT_TO_WRITE_SMALL_FILES_TO_DISK_DEFAULT = false;

  public static final String DFS_DB_FILE_MAX_SIZE_KEY = "dfs.db.file.max.size";
  public static final int DFS_DB_FILE_MAX_SIZE_DEFAULT = 64 * 1024;

  public static final String DFS_LEASE_CREATION_LOCKS_COUNT_KEY = "dfs.lease.creation.locks.count.key";
  public static final int DFS_LEASE_CREATION_LOCKS_COUNT_DEFAULT = 1000;

  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 = "dfs.bytes-per-checksum";
  public static final int     DFS_BYTES_PER_CHECKSUM_DEFAULT = 512;
  public static final String  DFS_USER_HOME_DIR_PREFIX_KEY = "dfs.user.home.dir.prefix";
  public static final String  DFS_USER_HOME_DIR_PREFIX_DEFAULT = "/user";
  public static final String  DFS_CHECKSUM_TYPE_KEY = "dfs.checksum.type";
  public static final String  DFS_CHECKSUM_TYPE_DEFAULT = "CRC32C";
  public static final String  DFS_HDFS_BLOCKS_METADATA_ENABLED = "dfs.datanode.hdfs-blocks-metadata.enabled";
  public static final boolean DFS_HDFS_BLOCKS_METADATA_ENABLED_DEFAULT = false;
  public static final String DFS_WEBHDFS_ACL_PERMISSION_PATTERN_DEFAULT =
      HdfsClientConfigKeys.DFS_WEBHDFS_ACL_PERMISSION_PATTERN_DEFAULT;

  // 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_DATANODE_BALANCE_BANDWIDTHPERSEC_KEY = "dfs.datanode.balance.bandwidthPerSec";
  public static final long    DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_DEFAULT = 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 = 5;
  public static final String  DFS_DATANODE_READAHEAD_BYTES_KEY = "dfs.datanode.readahead.bytes";
  public static final long    DFS_DATANODE_READAHEAD_BYTES_DEFAULT = 4 * 1024 * 1024; // 4MB
  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_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_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 String  DFS_NAMENODE_HTTP_PORT_KEY =
      HdfsClientConfigKeys.DFS_NAMENODE_HTTP_PORT_KEY;
  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 = "dfs.namenode.rpc-address";
  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_MAX_OBJECTS_KEY = "dfs.namenode.max.objects";
  public static final long    DFS_NAMENODE_MAX_OBJECTS_DEFAULT = 0;
  public static final String  DFS_NAMENODE_SAFEMODE_EXTENSION_KEY = "dfs.namenode.safemode.extension";
  public static final int     DFS_NAMENODE_SAFEMODE_EXTENSION_DEFAULT = 30000;
  public static final String  DFS_NAMENODE_SAFEMODE_THRESHOLD_PCT_KEY = "dfs.namenode.safemode.threshold-pct";
  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_HEARTBEAT_RECHECK_INTERVAL_KEY = "dfs.namenode.heartbeat.recheck-interval";
  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 = "dfs.namenode.accesstime.precision";
  public static final long    DFS_NAMENODE_ACCESSTIME_PRECISION_DEFAULT = 3600000;
  public static final String  DFS_NAMENODE_REPLICATION_CONSIDERLOAD_KEY = "dfs.namenode.replication.considerLoad";
  public static final boolean DFS_NAMENODE_REPLICATION_CONSIDERLOAD_DEFAULT = true;
  public static final String  DFS_NAMENODE_REPLICATION_INTERVAL_KEY = "dfs.namenode.replication.interval";
  public static final int     DFS_NAMENODE_REPLICATION_INTERVAL_DEFAULT = 3;
  public static final String  DFS_NAMENODE_REPLICATION_MIN_KEY = "dfs.namenode.replication.min";
  public static final int     DFS_NAMENODE_REPLICATION_MIN_DEFAULT = 1;
  public static final String  DFS_NAMENODE_REPLICATION_PENDING_TIMEOUT_SEC_KEY = "dfs.namenode.replication.pending.timeout-sec";
  public static final int     DFS_NAMENODE_REPLICATION_PENDING_TIMEOUT_SEC_DEFAULT = -1;
  public static final String  DFS_NAMENODE_REPLICATION_MAX_STREAMS_KEY = "dfs.namenode.replication.max-streams";
  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_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".toString();
  @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 = "dfs.permissions.enabled";
  public static final boolean DFS_PERMISSIONS_ENABLED_DEFAULT = true;
  public static final String  DFS_PERMISSIONS_SUPERUSERGROUP_KEY = "dfs.permissions.superusergroup";
  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_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_TRUSTSTORE_PASSWORD_KEY = "ssl.server.truststore.password";
  public static final String  DFS_NAMENODE_NAME_DIR_RESTORE_KEY = "dfs.namenode.name.dir.restore";
  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_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_LIST_LIMIT = "dfs.ls.limit";
  public static final int     DFS_LIST_LIMIT_DEFAULT = Integer.MAX_VALUE; //1000; [HopsFS] Jira Hops-45
  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_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;

  /** 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;
  
  // 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;
  // no limit
  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 = 10*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*1024;
  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 = XAttrStorage.getDefaultXAttrSize();
  public static final int     DFS_NAMENODE_MAX_XATTR_SIZE_HARD_LIMIT = XAttrStorage.getMaxXAttrSize();
  public static final String  DFS_DIR_XATTR_LOCK_BATCH_SIZE_KEY = "dfs.dir.xattr.lock.batch.size";
  public static final int     DFS_DIR_XATTR_LOCK_BATCH_SIZE_DEFAULT = 1000;

  //Following keys have no defaults
  public static final String  DFS_DATANODE_DATA_DIR_KEY = "dfs.datanode.data.dir";
  public static final String  DFS_NAMENODE_HTTPS_PORT_KEY = 
      HdfsClientConfigKeys.DFS_NAMENODE_HTTPS_PORT_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_METRICS_SESSION_ID_KEY = "dfs.metrics.session-id";
  public static final String  DFS_METRICS_PERCENTILES_INTERVALS_KEY = "dfs.metrics.percentiles.intervals";
  public static final String  DFS_DATANODE_HOST_NAME_KEY = "dfs.datanode.hostname";
  public static final String  DFS_NAMENODE_HOSTS_KEY = "dfs.namenode.hosts";
  public static final String  DFS_NAMENODE_HOSTS_EXCLUDE_KEY = "dfs.namenode.hosts.exclude";
  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_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_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_BALANCER_DISPATCHERTHREADS_KEY = "dfs.balancer.dispatcherThreads";
  public static final int     DFS_BALANCER_DISPATCHERTHREADS_DEFAULT = 200;

  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_DATANODE_ADDRESS_KEY = "dfs.datanode.address";
  public static final int     DFS_DATANODE_DEFAULT_PORT = 50010;
  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_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_KEY = "dfs.datanode.du.reserved";
  public static final long    DFS_DATANODE_DU_RESERVED_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 = 50075;
  public static final String  DFS_DATANODE_HTTP_ADDRESS_DEFAULT = "0.0.0.0:" + DFS_DATANODE_HTTP_DEFAULT_PORT;
  public static final String  DFS_DATANODE_MAX_RECEIVER_THREADS_KEY = "dfs.datanode.max.transfer.threads";
  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 = 0;
  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_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_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_SUPPORT_APPEND_KEY = "dfs.support.append";
  public static final boolean DFS_SUPPORT_APPEND_DEFAULT = true;
  public static final String  DFS_HTTPS_ENABLE_KEY = "dfs.https.enable";
  public static final boolean DFS_HTTPS_ENABLE_DEFAULT = false;
  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 = 50475;
  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 = 50020;
  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_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 = 450L;
  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_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_DF_INTERVAL_KEY = "dfs.df.interval";
  public static final int     DFS_DF_INTERVAL_DEFAULT = 60000;
  public static final String  DFS_BLOCKREPORT_INTERVAL_MSEC_KEY = "dfs.blockreport.intervalMsec";
  public static final long    DFS_BLOCKREPORT_INTERVAL_MSEC_DEFAULT = 60 * 60 * 1000L;
  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_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;


  //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 = "dfs.datanode.socket.write.timeout";
  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 = "dfs.datanode.kerberos.principal";
  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 = "dfs.short.circuit.shared.memory.watcher.interrupt.check.ms";
  public static final int     DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT = 60000;
  public static final String  DFS_NAMENODE_KEYTAB_FILE_KEY = "dfs.namenode.keytab.file";
  public static final String  DFS_NAMENODE_KERBEROS_PRINCIPAL_KEY = "dfs.namenode.kerberos.principal";
  public static final String  DFS_NAMENODE_KERBEROS_INTERNAL_SPNEGO_PRINCIPAL_KEY = "dfs.namenode.kerberos.internal.spnego.principal";
  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_NAMESERVICES = "dfs.nameservices";
  public static final String  DFS_NAMESERVICE_ID = "dfs.nameservice.id";
  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_DB_CHECK_MAX_TRIES = "dfs.namenode.db.check.max.tries";
  public static final int     DFS_NAMENODE_DB_CHECK_MAX_TRIES_DEFAULT = 3;
  
  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_NAMENODE_RESOURCE_CHECK_THRESHOLD = "dfs.namenode.resource.check.threshold";
  public static final double  DFS_NAMENODE_RESOURCE_CHECK_THRESHOLD_DEFAULT = 0.9;
  public static final String  DFS_NAMENODE_RESOURCE_CHECK_PRETHRESHOLD = "dfs.namenode.resource.check.prethreshold";
  public static final double  DFS_NAMENODE_RESOURCE_CHECK_PRETHRESHOLD_DEFAULT = DFS_NAMENODE_RESOURCE_CHECK_THRESHOLD_DEFAULT - (DFS_NAMENODE_RESOURCE_CHECK_THRESHOLD_DEFAULT * 0.1);
  
  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_BLOCK_LOCAL_PATH_ACCESS_USER_KEY = "dfs.block.local-path-access.user";
  public static final String DFS_DOMAIN_SOCKET_PATH_KEY = "dfs.domain.socket.path";
  public static final String 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;
  
  // 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_ENCRYPT_DATA_TRANSFER_CIPHER_KEY_BITLENGTH_KEY = "dfs.encrypt.data.transfer.cipher.key.bitlength";
  public static final int    DFS_ENCRYPT_DATA_TRANSFER_CIPHER_KEY_BITLENGTH_DEFAULT = 128;
  public static final String DFS_ENCRYPT_DATA_TRANSFER_CIPHER_SUITES_KEY = "dfs.encrypt.data.transfer.cipher.suites";
  public static final String DFS_DATA_ENCRYPTION_ALGORITHM_KEY = "dfs.encrypt.data.transfer.algorithm";
  public static final String DFS_TRUSTEDCHANNEL_RESOLVER_CLASS = "dfs.trustedchannel.resolver.class";
  public static final String DFS_DATA_TRANSFER_PROTECTION_KEY = "dfs.data.transfer.protection";
  public static final String DFS_DATA_TRANSFER_PROTECTION_DEFAULT = "";
  public static final String DFS_DATA_TRANSFER_SASL_PROPS_RESOLVER_CLASS_KEY = "dfs.data.transfer.saslproperties.resolver.class";
  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 String DFS_ENCRYPTION_KEY_PROVIDER_URI = "dfs.encryption.key.provider.uri";
  
  // Hash bucket config
  public static final String DFS_NUM_BUCKETS_KEY = "dfs.blockreport.numbuckets";
  public static final int    DFS_NUM_BUCKETS_DEFAULT = 1000;
  
  public static final String DFS_BLOCK_FETCHER_NB_THREADS = "dfs.block.fetcher.nb.threads";
  public static final int    DFS_BLOCK_FETCHER_NB_THREADS_DEFAULT = 10;
  
  public static final String DFS_BLOCK_FETCHER_BUCKETS_PER_THREAD = "dfs.block.fetcher.buckets.per.thread";
  public static final int    DFS_BLOCK_FETCHER_BUCKETS_PER_THREADS_DEFAULT = 1;
  
  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

  // 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;
  
  // Socket factory for the DFSClient to use when connecting to DataXceiver
  // See HOPS-1525
  public static final String DFS_CLIENT_XCEIVER_SOCKET_FACTORY_CLASS_KEY = "dfs.client.xceiver.socket.factory.class";
  public static final String DEFAULT_DFS_CLIENT_XCEIVER_FACTORY_CLASS = "org.apache.hadoop.net.StandardSocketFactory";
  
  // 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;

  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 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 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_CLIENT_KEY_PROVIDER_CACHE_EXPIRY_MS =
      "dfs.client.key.provider.cache.expiry";
  // 10 days
  public static final long DFS_CLIENT_KEY_PROVIDER_CACHE_EXPIRY_DEFAULT =
      TimeUnit.DAYS.toMillis(10);
  
  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;
  
  @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;



  public static final String  DFS_CLIENT_WRITE_PACKET_SIZE_KEY = "dfs.client-write-packet-size";
  public static final int     DFS_CLIENT_WRITE_PACKET_SIZE_DEFAULT = 64*1024;

  public static final String  DFS_CLIENT_SOCKET_TIMEOUT_KEY = "dfs.client.socket-timeout";
  public static final String  DFS_CLIENT_SOCKET_CACHE_CAPACITY_KEY = "dfs.client.socketcache.capacity";
  public static final int     DFS_CLIENT_SOCKET_CACHE_CAPACITY_DEFAULT = 16;
  public static final String  DFS_CLIENT_SOCKET_CACHE_EXPIRY_MSEC_KEY = "dfs.client.socketcache.expiryMsec";
  public static final long    DFS_CLIENT_SOCKET_CACHE_EXPIRY_MSEC_DEFAULT = 3000;

  public static final String  DFS_CLIENT_USE_DN_HOSTNAME = "dfs.client.use.datanode.hostname";
  public static final boolean DFS_CLIENT_USE_DN_HOSTNAME_DEFAULT = false;
  public static final String  DFS_CLIENT_CACHE_DROP_BEHIND_WRITES = "dfs.client.cache.drop.behind.writes";
  public static final String  DFS_CLIENT_CACHE_DROP_BEHIND_READS = "dfs.client.cache.drop.behind.reads";
  public static final String  DFS_CLIENT_CACHE_READAHEAD = "dfs.client.cache.readahead";
  public static final String  DFS_CLIENT_CACHED_CONN_RETRY_KEY = "dfs.client.cached.conn.retry";
  public static final int     DFS_CLIENT_CACHED_CONN_RETRY_DEFAULT = 3;

  public static final String  DFS_CLIENT_CONTEXT = "dfs.client.context";
  public static final String  DFS_CLIENT_CONTEXT_DEFAULT = "default";
  public static final String  DFS_CLIENT_FILE_BLOCK_STORAGE_LOCATIONS_NUM_THREADS = "dfs.client.file-block-storage-locations.num-threads";
  public static final int     DFS_CLIENT_FILE_BLOCK_STORAGE_LOCATIONS_NUM_THREADS_DEFAULT = 10;
  public static final String  DFS_CLIENT_FILE_BLOCK_STORAGE_LOCATIONS_TIMEOUT_MS = "dfs.client.file-block-storage-locations.timeout.millis";
  public static final int     DFS_CLIENT_FILE_BLOCK_STORAGE_LOCATIONS_TIMEOUT_MS_DEFAULT = 1000;
  
  public static final String  DFS_CLIENT_DATANODE_RESTART_TIMEOUT_KEY = "dfs.client.datanode-restart.timeout";
  public static final long    DFS_CLIENT_DATANODE_RESTART_TIMEOUT_DEFAULT = 30;

  public static final String  DFS_CLIENT_HTTPS_KEYSTORE_RESOURCE_KEY = "dfs.client.https.keystore.resource";
  public static final String  DFS_CLIENT_HTTPS_KEYSTORE_RESOURCE_DEFAULT = "ssl-client.xml";
  public static final String  DFS_CLIENT_HTTPS_NEED_AUTH_KEY = "dfs.client.https.need-auth";
  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.
  public static final String  DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_KEY = "dfs.client.max.block.acquire.failures";
  public static final int     DFS_CLIENT_MAX_BLOCK_ACQUIRE_FAILURES_DEFAULT = 3;

  public static final String  DFS_CLIENT_USE_LEGACY_BLOCKREADER = "dfs.client.use.legacy.blockreader";
  public static final boolean DFS_CLIENT_USE_LEGACY_BLOCKREADER_DEFAULT = false;
  public static final String  DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL = "dfs.client.use.legacy.blockreader.local";
  public static final boolean DFS_CLIENT_USE_LEGACY_BLOCKREADERLOCAL_DEFAULT = false;
  
  public static final String  DFS_CLIENT_LOCAL_INTERFACES = "dfs.client.local.interfaces";


  public static final String  DFS_CLIENT_DOMAIN_SOCKET_DATA_TRAFFIC = "dfs.client.domain.socket.data.traffic";
  public static final boolean DFS_CLIENT_DOMAIN_SOCKET_DATA_TRAFFIC_DEFAULT = false;

  // The number of NN response dropped by client proactively in each RPC call.
  // For testing NN retry cache, we can set this property with positive value.
  public static final String  DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY = "dfs.client.test.drop.namenode.response.number";
  public static final int     DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_DEFAULT = 0;
  public static final String  DFS_CLIENT_SLOW_IO_WARNING_THRESHOLD_KEY =
      "dfs.client.slow.io.warning.threshold.ms";
  public static final long    DFS_CLIENT_SLOW_IO_WARNING_THRESHOLD_DEFAULT = 30000;
  //Availability zones
  public static final String  DFS_LOCATION_DOMAIN_ID = "dfs.locationDomainId";
  public static final byte    DFS_LOCATION_DOMAIN_ID_DEFAULT = 0;
  
  private static final String FS_SECURITY_ACTIONS_PREFIX = "dfs.security-actions.";
  
  public static final String FS_SECURITY_ACTIONS_ACTOR_KEY = FS_SECURITY_ACTIONS_PREFIX + "actor-class";
  public static final String DEFAULT_FS_SECURITY_ACTIONS_ACTOR = "io.hops.common.security.HopsworksFsSecurityActions";
  
  private static final String FS_SECURITY_ACTIONS_X509 = FS_SECURITY_ACTIONS_PREFIX + "x509.";
  
  public static final String FS_SECURITY_ACTIONS_X509_PATH_KEY = FS_SECURITY_ACTIONS_X509 + "get-path";
  public static final String DEFAULT_FS_SECURITY_ACTIONS_X509_PATH = "/hopsworks-api/api/admin/credentials/x509";
  
  public static final String  DFS_DB_REPLICATION_FACTOR = "dfs.db.replication";
  public static final byte    DFS_DB_REPLICATION_FACTOR_DEFAULT = 1;
}
