HDFS Commands Guide-CFANZ编程社区

HDFS Commands Guide

Overview
User Commands

classpath
dfs
fetchdt
fsck
getconf
groups
lsSnapshottableDir
jmxget
oev
oiv
oiv_legacy
snapshotDiff
version

Administration Commands

balancer
cacheadmin
crypto
datanode
dfsadmin
haadmin
journalnode
mover
namenode
nfs3
portmap
secondarynamenode
storagepolicies
zkfc

Debug Commands

verify
recoverLease

Overview

All HDFS commands are invoked by the bin/hdfs

Usage: hdfs [SHELL_OPTIONS] COMMAND [GENERIC_OPTIONS] [COMMAND_OPTIONS]

Hadoop has an option parsing framework that employs parsing generic options as well as running classes.

COMMAND_OPTIONS	Description
--config --loglevel	The common set of shell options. These are documented on the Commands Manual page.
GENERIC_OPTIONS	The common set of options supported by multiple commands. See the Hadoop Commands Manual for more information.
COMMAND COMMAND_OPTIONS	Various commands with their options are described in the following sections. The commands have been grouped into User Commands andAdministration Commands.

User Commands

Commands useful for users of a hadoop cluster.

classpath

Usage: hdfs classpath

Prints the class path needed to get the Hadoop jar and the required libraries

dfs

Usage: hdfs dfs [COMMAND [COMMAND_OPTIONS]]

Run a filesystem command on the file system supported in Hadoop. The various COMMAND_OPTIONS can be found at File System Shell Guide.

fetchdt

Usage: hdfs fetchdt [--webservice <namenode_http_addr>] <path>

COMMAND_OPTION	Description
--webservice https_address	use http protocol instead of RPC
fileName	File name to store the token into.

Gets Delegation Token from a NameNode. See fetchdt for more info.

fsck

Usage:

hdfs fsck <path>
          [-list-corruptfileblocks |
          [-move | -delete | -openforwrite]
          [-files [-blocks [-locations | -racks]]]
          [-includeSnapshots]
          [-storagepolicies] [-blockId <blk_Id>]

COMMAND_OPTION	Description
path	Start checking from this path.
-delete	Delete corrupted files.
-files	Print out files being checked.
-files -blocks	Print out the block report
-files -blocks -locations	Print out locations for every block.
-files -blocks -racks	Print out network topology for data-node locations.
-includeSnapshots	Include snapshot data if the given path indicates a snapshottable directory or there are snapshottable directories under it.
-list-corruptfileblocks	Print out list of missing blocks and files they belong to.
-move	Move corrupted files to /lost+found.
-openforwrite	Print out files opened for write.
-storagepolicies	Print out storage policy summary for the blocks.
-blockId	Print out information about the block.

Runs the HDFS filesystem checking utility. See fsck for more info.

getconf

Usage:

hdfs getconf -namenodes
   hdfs getconf -secondaryNameNodes
   hdfs getconf -backupNodes
   hdfs getconf -includeFile
   hdfs getconf -excludeFile
   hdfs getconf -nnRpcAddresses
   hdfs getconf -confKey [key]

COMMAND_OPTION	Description
-namenodes	gets list of namenodes in the cluster.
-secondaryNameNodes	gets list of secondary namenodes in the cluster.
-backupNodes	gets list of backup nodes in the cluster.
-includeFile	gets the include file path that defines the datanodes that can join the cluster.
-excludeFile	gets the exclude file path that defines the datanodes that need to decommissioned.
-nnRpcAddresses	gets the namenode rpc addresses
-confKey	gets a specific key from the configuration

Gets configuration information from the configuration directory, post-processing.

groups

Usage: hdfs groups [username ...]

Returns the group information given one or more usernames.

lsSnapshottableDir

Usage: hdfs lsSnapshottableDir [-help]

COMMAND_OPTION	Description
-help	print help

Get the list of snapshottable directories. When this is run as a super user, it returns all snapshottable directories. Otherwise it returns those directories that are owned by the current user.

jmxget

Usage: hdfs jmxget [-localVM ConnectorURL | -port port | -server mbeanserver | -service service]

COMMAND_OPTION	Description
-help	print help
-localVM	connect to the VM on the same machine
-port mbean server port	specify mbean server port, if missing it will try to connect to MBean Server in the same VM
-service	specify jmx service, either DataNode or NameNode, the default

Dump JMX information from a service.

oev

Usage: hdfs oev [OPTIONS] -i INPUT_FILE -o OUTPUT_FILE

Required command line arguments:

COMMAND_OPTION	Description
-i,--inputFile arg	edits file to process, xml (case insensitive) extension means XML format, any other filename means binary format
-o,--outputFile arg	Name of output file. If the specified file exists, it will be overwritten, format of the file is determined by -p option

Optional command line arguments:

COMMAND_OPTION	Description
-f,--fix-txids	Renumber the transaction IDs in the input, so that there are no gaps or invalid transaction IDs.
-h,--help	Display usage information and exit
-r,--ecover	When reading binary edit logs, use recovery mode. This will give you the chance to skip corrupt parts of the edit log.
-p,--processor arg	Select which type of processor to apply against image file, currently supported processors are: binary (native binary format that Hadoop uses), xml (default, XML format), stats (prints statistics about edits file)
-v,--verbose	More verbose output, prints the input and output filenames, for processors that write to a file, also output to screen. On large image files this will dramatically increase processing time (default is false).

Hadoop offline edits viewer.

oiv

Usage: hdfs oiv [OPTIONS] -i INPUT_FILE

Required command line arguments:

COMMAND_OPTION	Description
-i,--inputFile arg	edits file to process, xml (case insensitive) extension means XML format, any other filename means binary format

Optional command line arguments:

COMMAND_OPTION	Description
-h,--help	Display usage information and exit
-o,--outputFile arg	Name of output file. If the specified file exists, it will be overwritten, format of the file is determined by -p option
-p,--processor arg	Select which type of processor to apply against image file, currently supported processors are: binary (native binary format that Hadoop uses), xml (default, XML format), stats (prints statistics about edits file)

Hadoop Offline Image Viewer for newer image files.

oiv_legacy

Usage: hdfs oiv_legacy [OPTIONS] -i INPUT_FILE -o OUTPUT_FILE

COMMAND_OPTION	Description
-h,--help	Display usage information and exit
-i,--inputFile arg	edits file to process, xml (case insensitive) extension means XML format, any other filename means binary format
-o,--outputFile arg	Name of output file. If the specified file exists, it will be overwritten, format of the file is determined by -p option

Hadoop offline image viewer for older versions of Hadoop.

snapshotDiff

Usage: hdfs snapshotDiff <path> <fromSnapshot> <toSnapshot>

Determine the difference between HDFS snapshots. See the HDFS Snapshot Documentation for more information.

version

Usage: hdfs version

Prints the version.

Administration Commands

Commands useful for administrators of a hadoop cluster.

balancer

Usage:

hdfs balancer
          [-threshold <threshold>]
          [-policy <policy>]
          [-exclude [-f <hosts-file> | <comma-separated list of hosts>]]
          [-include [-f <hosts-file> | <comma-separated list of hosts>]]
          [-idleiterations <idleiterations>]

COMMAND_OPTION	Description
-policy	datanode (default): Cluster is balanced if each datanode is balanced. blockpool: Cluster is balanced if each block pool in each datanode is balanced.
-threshold	Percentage of disk capacity. This overwrites the default threshold.
-exclude -f	Excludes the specified datanodes from being balanced by the balancer.
-include -f	Includes only the specified datanodes to be balanced by the balancer.
-idleiterations	Maximum number of idle iterations before exit. This overwrites the default idleiterations(5).

Runs a cluster balancing utility. An administrator can simply press Ctrl-C to stop the rebalancing process. See Balancer for more details.

Note that the blockpool policy is more strict than the datanode

cacheadmin

Usage: hdfs cacheadmin -addDirective -path <path> -pool <pool-name> [-force] [-replication <replication>] [-ttl <time-to-live>]

See the HDFS Cache Administration Documentation for more information.

crypto

Usage:

hdfs crypto -createZone -keyName <keyName> -path <path>
  hdfs crypto -help <command-name>
  hdfs crypto -listZones

See the HDFS Transparent Encryption Documentation for more information.

datanode

Usage: hdfs datanode [-regular | -rollback | -rollingupgrace rollback]

COMMAND_OPTION	Description
-regular	Normal datanode startup (default).
-rollback	Rollback the datanode to the previous version. This should be used after stopping the datanode and distributing the old hadoop version.
-rollingupgrade	Rollback a rolling upgrade operation.

Runs a HDFS datanode.

dfsadmin

Usage:

hdfs dfsadmin [GENERIC_OPTIONS]
          [-report [-live] [-dead] [-decommissioning]]
          [-safemode enter | leave | get | wait]
          [-saveNamespace]
          [-rollEdits]
          [-restoreFailedStorage true |false |check]
          [-refreshNodes]
          [-setQuota <quota> <dirname>...<dirname>]
          [-clrQuota <dirname>...<dirname>]
          [-setSpaceQuota <quota> <dirname>...<dirname>]
          [-clrSpaceQuota <dirname>...<dirname>]
          [-setStoragePolicy <path> <policyName>]
          [-getStoragePolicy <path>]
          [-finalizeUpgrade]
          [-rollingUpgrade [<query> |<prepare> |<finalize>]]
          [-metasave filename]
          [-refreshServiceAcl]
          [-refreshUserToGroupsMappings]
          [-refreshSuperUserGroupsConfiguration]
          [-refreshCallQueue]
          [-refresh <host:ipc_port> <key> [arg1..argn]]
          [-reconfig <datanode |...> <host:ipc_port> <start |status>]
          [-printTopology]
          [-refreshNamenodes datanodehost:port]
          [-deleteBlockPool datanode-host:port blockpoolId [force]]
          [-setBalancerBandwidth <bandwidth in bytes per second>]
          [-allowSnapshot <snapshotDir>]
          [-disallowSnapshot <snapshotDir>]
          [-fetchImage <local directory>]
          [-shutdownDatanode <datanode_host:ipc_port> [upgrade]]
          [-getDatanodeInfo <datanode_host:ipc_port>]
          [-triggerBlockReport [-incremental] <datanode_host:ipc_port>]
          [-help [cmd]]

COMMAND_OPTION	Description
-report [-live] [-dead] [-decommissioning]	Reports basic filesystem information and statistics. Optional flags may be used to filter the list of displayed DataNodes.
-safemode	Safe mode maintenance command. Safe mode is a Namenode state in which it 1. does not accept changes to the name space (read-only) 2. does not replicate or delete blocks. Safe mode is entered automatically at Namenode startup, and leaves safe mode automatically when the configured minimum percentage of blocks satisfies the minimum replication condition. Safe mode can also be entered manually, but then it can only be turned off manually as well.
-saveNamespace	Save current namespace into storage directories and reset edits log. Requires safe mode.
-rollEdits	Rolls the edit log on the active NameNode.
-restoreFailedStoragetrue\|false\|check	This option will turn on/off automatic attempt to restore failed storage replicas. If a failed storage becomes available again the system will attempt to restore edits and/or fsimage during checkpoint. ‘check’ option will return current setting.
-refreshNodes	Re-read the hosts and exclude files to update the set of Datanodes that are allowed to connect to the Namenode and those that should be decommissioned or recommissioned.
-setQuota	See HDFS Quotas Guide for the detail.
-clrQuota	See HDFS Quotas Guide for the detail.
-setSpaceQuota	See HDFS Quotas Guide for the detail.
-clrSpaceQuota	See HDFS Quotas Guide for the detail.
-setStoragePolicy	Set a storage policy to a file or a directory.
-getStoragePolicy	Get the storage policy of a file or a directory.
-finalizeUpgrade	Finalize upgrade of HDFS. Datanodes delete their previous version working directories, followed by Namenode doing the same. This completes the upgrade process.
-rollingUpgrade	See Rolling Upgrade document for the detail.
-metasave	Save Namenode’s primary data structures to filename in the directory specified by hadoop.log.dir property. filename is overwritten if it exists. filename will contain one line for each of the following 1. Datanodes heart beating with Namenode 2. Blocks waiting to be replicated 3. Blocks currently being replicated 4. Blocks waiting to be deleted
-refreshServiceAcl	Reload the service-level authorization policy file.
-refreshUserToGroupsMappings	Refresh user-to-groups mappings.
-refreshSuperUserGroupsConfiguration	Refresh superuser proxy groups mappings
-refreshCallQueue	Reload the call queue from config.
-refresh	Triggers a runtime-refresh of the resource specified by <key> on <host:ipc_port>. All other args after are sent to the host.
-reconfig	Start reconfiguration or get the status of an ongoing reconfiguration. The second parameter specifies the node type. Currently, only reloading DataNode’s configuration is supported.
-printTopology	Print a tree of the racks and their nodes as reported by the Namenode
-refreshNamenodesdatanodehost:port	For the given datanode, reloads the configuration files, stops serving the removed block-pools and starts serving new block-pools.
-deleteBlockPool	If force is passed, block pool directory for the given blockpool id on the given datanode is deleted along with its contents, otherwise the directory is deleted only if it is empty. The command will fail if datanode is still serving the block pool. Refer to refreshNamenodes to shutdown a block pool service on a datanode.
-setBalancerBandwidth	Changes the network bandwidth used by each datanode during HDFS block balancing. <bandwidth> is the maximum number of bytes per second that will be used by each datanode. This value overrides the dfs.balance.bandwidthPerSec parameter. NOTE: The new value is not persistent on the DataNode.
-allowSnapshot	Allowing snapshots of a directory to be created. If the operation completes successfully, the directory becomes snapshottable. See theHDFS Snapshot Documentation for more information.
-disallowSnapshot	Disallowing snapshots of a directory to be created. All snapshots of the directory must be deleted before disallowing snapshots. See theHDFS Snapshot Documentation for more information.
-fetchImage	Downloads the most recent fsimage from the NameNode and saves it in the specified local directory.
-shutdownDatanode<datanode_host:ipc_port> [upgrade]	Submit a shutdown request for the given datanode. See Rolling Upgrade document for the detail.
-getDatanodeInfo<datanode_host:ipc_port>	Get the information about the given datanode. See Rolling Upgrade document for the detail.
-triggerBlockReport [-incremental]<datanode_host:ipc_port>	Trigger a block report for the given datanode. If ‘incremental’ is specified, it will be otherwise, it will be a full block report.
-help	Displays help for the given command or all commands if none is specified.

Runs a HDFS dfsadmin client.

haadmin

Usage:

hdfs haadmin -checkHealth <serviceId>
    hdfs haadmin -failover [--forcefence] [--forceactive] <serviceId> <serviceId>
    hdfs haadmin -getServiceState <serviceId>
    hdfs haadmin -help <command>
    hdfs haadmin -transitionToActive <serviceId> [--forceactive]
    hdfs haadmin -transitionToStandby <serviceId>

COMMAND_OPTION	Description
-checkHealth	check the health of the given NameNode
-failover	initiate a failover between two NameNodes
-getServiceState	determine whether the given NameNode is Active or Standby
-transitionToActive	transition the state of the given NameNode to Active (Warning: No fencing is done)
-transitionToStandby	transition the state of the given NameNode to Standby (Warning: No fencing is done)

See HDFS HA with NFS or HDFS HA with QJM for more information on this command.

journalnode

Usage: hdfs journalnode

This comamnd starts a journalnode for use with HDFS HA with QJM.

mover

Usage: hdfs mover [-p <files/dirs> | -f <local file name>]

COMMAND_OPTION	Description
-f	Specify a local file containing a list of HDFS files/dirs to migrate.
-p	Specify a space separated list of HDFS files/dirs to migrate.

Runs the data migration utility. See Mover for more details.

Note that, when both -p and -f options are omitted, the default path is the root directory.

namenode

Usage:

hdfs namenode [-backup] |
          [-checkpoint] |
          [-format [-clusterid cid ] [-force] [-nonInteractive] ] |
          [-upgrade [-clusterid cid] [-renameReserved<k-v pairs>] ] |
          [-upgradeOnly [-clusterid cid] [-renameReserved<k-v pairs>] ] |
          [-rollback] |
          [-rollingUpgrade <downgrade |rollback> ] |
          [-finalize] |
          [-importCheckpoint] |
          [-initializeSharedEdits] |
          [-bootstrapStandby] |
          [-recover [-force] ] |
          [-metadataVersion ]

COMMAND_OPTION	Description
-backup	Start backup node.
-checkpoint	Start checkpoint node.
-format [-clusterid cid] [-force][-nonInteractive]	Formats the specified NameNode. It starts the NameNode, formats it and then shut it down. -force option formats if the name directory exists. -nonInteractive option aborts if the name directory exists, unless -force option is specified.
-upgrade [-clusterid cid] [-renameReserved	Namenode should be started with upgrade option after the distribution of new Hadoop version.
-upgradeOnly [-clusterid cid] [-renameReserved	Upgrade the specified NameNode and then shutdown it.
-rollback	Rollback the NameNode to the previous version. This should be used after stopping the cluster and distributing the old Hadoop version.
-rollingUpgrade<downgrade\|rollback\|started>	See Rolling Upgrade document for the detail.
-finalize	Finalize will remove the previous state of the files system. Recent upgrade will become permanent. Rollback option will not be available anymore. After finalization it shuts the NameNode down.
-importCheckpoint	Loads image from a checkpoint directory and save it into the current one. Checkpoint dir is read from property fs.checkpoint.dir
-initializeSharedEdits	Format a new shared edits dir and copy in enough edit log segments so that the standby NameNode can start up.
-bootstrapStandby	Allows the standby NameNode’s storage directories to be bootstrapped by copying the latest namespace snapshot from the active NameNode. This is used when first configuring an HA cluster.
-recover [-force]	Recover lost metadata on a corrupt filesystem. See HDFS User Guide for the detail.
-metadataVersion	Verify that configured directories exist, then print the metadata versions of the software and the image.

Runs the namenode. More info about the upgrade, rollback and finalize is at Upgrade Rollback.

nfs3

Usage: hdfs nfs3

This comamnd starts the NFS3 gateway for use with the HDFS NFS3 Service.

portmap

Usage: hdfs portmap

This comamnd starts the RPC portmap for use with the HDFS NFS3 Service.

secondarynamenode

Usage: hdfs secondarynamenode [-checkpoint [force]] | [-format] | [-geteditsize]

COMMAND_OPTION	Description
-checkpoint	force
-format	Format the local storage during startup.
-geteditsize	Prints the number of uncheckpointed transactions on the NameNode.

Runs the HDFS secondary namenode. See Secondary Namenode for more info.

storagepolicies

Usage: hdfs storagepolicies

Lists out all storage policies. See the HDFS Storage Policy Documentation for more information.

zkfc

Usage: hdfs zkfc [-formatZK [-force] [-nonInteractive]]

COMMAND_OPTION	Description
-formatZK	Format the Zookeeper instance
-h	Display help

This comamnd starts a Zookeeper Failover Controller process for use with HDFS HA with QJM.

Debug Commands

Useful commands to help administrators debug HDFS issues, like validating block files and calling recoverLease.

verify

Usage: hdfs debug verify [-meta <metadata-file>] [-block <block-file>]

COMMAND_OPTION	Description
-block block-file	Optional parameter to specify the absolute path for the block file on the local file system of the data node.
-meta metadata-file	Absolute path for the metadata file on the local file system of the data node.

Verify HDFS metadata and block files. If a block file is specified, we will verify that the checksums in the metadata file match the block file.

recoverLease

Usage: hdfs debug recoverLease [-path <path>] [-retries <num-retries>]

COMMAND_OPTION	Description
-path path]	HDFS path for which to recover the lease.
-retries num-retries]	Number of times the client will retry calling recoverLease. The default number of retries is 1.

Recover the lease on the specified path. The path must reside on an HDFS filesystem. The default number of retries is 1.