All HDFS commands are invoked by the bin/hdfs script. Running the hdfs script without any arguments prints the description for all commands.
Usage: hdfs [--config confdir] [COMMAND] [GENERIC_OPTIONS] [COMMAND_OPTIONS]
Hadoop has an option parsing framework that employs parsing generic options as well as running classes.
| COMMAND_OPTION | Description |
|---|---|
| --config confdir | Overwrites the default Configuration directory. Default is $HADOOP_HOME/conf. |
| GENERIC_OPTIONS | The common set of options supported by multiple commands. Full list is here. |
| COMMAND_OPTIONS | Various commands with their options are described in the following sections. The commands have been grouped into and . |
Commands useful for users of a hadoop cluster.
Usage: hdfs dfs [GENERIC_OPTIONS] [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.
Gets Delegation Token from a NameNode. See fetchdt for more info.
Usage: hdfs fetchdt [GENERIC_OPTIONS] [--webservice <namenode_http_addr>] <path>
| COMMAND_OPTION | Description |
|---|---|
| fileName | File name to store the token into. |
| --webservice https_address | use http protocol instead of RPC |
Runs a HDFS filesystem checking utility. See fsck for more info.
Usage: hdfs fsck [GENERIC_OPTIONS] <path> [-list-corruptfileblocks | [-move | -delete | -openforwrite] [-files [-blocks [-locations | -racks]]]] [-includeSnapshots]
| COMMAND_OPTION | Description |
|---|---|
| path | Start checking from this path. |
| -move | Move corrupted files to /lost+found |
| -delete | Delete corrupted files. |
| -files | Print out files being checked. |
| -openforwrite | Print out files opened for write. |
| -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. |
| -blocks | Print out block report. |
| -locations | Print out locations for every block. |
| -racks | Print out network topology for data-node locations. |
Commands useful for administrators of a hadoop cluster.
Runs a cluster balancing utility. An administrator can simply press Ctrl-C to stop the rebalancing process. See Balancer for more details.
Usage: hdfs balancer [-threshold <threshold>] [-policy <policy>]
| COMMAND_OPTION | Description |
|---|---|
| -threshold threshold | Percentage of disk capacity. This overwrites the default threshold. |
| -policy policy | datanode (default): Cluster is balanced if each datanode is balanced. blockpool: Cluster is balanced if each block pool in each datanode is balanced. |
Note that the blockpool policy is more strict than the datanode policy.
Runs a HDFS 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 | Rollback a rolling upgrade operation. |
Runs a HDFS dfsadmin client.
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]]
[-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>]
[-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 enter|leave|get|wait | 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. |
| -restoreFailedStorage true|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 <quota> <dirname>...<dirname> | See HDFS Quotas Guide for the detail. |
| -clrQuota <dirname>...<dirname> | See HDFS Quotas Guide for the detail. |
| -setSpaceQuota <quota> <dirname>...<dirname> | See HDFS Quotas Guide for the detail. |
| -clrSpaceQuota <dirname>...<dirname> | See HDFS Quotas Guide for the detail. |
| -setStoragePolicy <path> <policyName> | Set a storage policy to a file or a directory. |
| -getStoragePolicy <path> | 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 [<query>|<prepare>|<finalize>] | See Rolling Upgrade document for the detail. |
| -metasave filename | 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 <host:ipc_port> <key> [arg1..argn] | Triggers a runtime-refresh of the resource specified by <key> on <host:ipc_port>. All other args after are sent to the host. |
| -printTopology | Print a tree of the racks and their nodes as reported by the Namenode |
| -refreshNamenodes datanodehost:port | For the given datanode, reloads the configuration files, stops serving the removed block-pools and starts serving new block-pools. |
| -deleteBlockPool datanode-host:port blockpoolId [force] | 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 <bandwidth in bytes per second> | 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 <snapshotDir> | Allowing snapshots of a directory to be created. If the operation completes successfully, the directory becomes snapshottable. |
| -disallowSnapshot <snapshotDir> | Disallowing snapshots of a directory to be created. All snapshots of the directory must be deleted before disallowing snapshots. |
| -fetchImage <local directory> | 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. |
| -help [cmd] | Displays help for the given command or all commands if none is specified. |
Runs the data migration utility. See Mover for more details.
Usage: hdfs mover [-p <files/dirs> | -f <local file name>]
| COMMAND_OPTION | Description |
|---|---|
| -p <files/dirs> | Specify a space separated list of HDFS files/dirs to migrate. |
| -f <local file> | Specify a local file containing a list of HDFS files/dirs to migrate. |
Note that, when both -p and -f options are omitted, the default path is the root directory.
Runs the namenode. More info about the upgrade, rollback and finalize is at Upgrade Rollback.
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<k-v pairs>] | Namenode should be started with upgrade option after the distribution of new Hadoop version. |
| -upgradeOnly [-clusterid cid] [-renameReserved<k-v pairs>] | 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 HDFS secondary namenode. See Secondary Namenode for more info.
Usage: hdfs secondarynamenode [-checkpoint [force]] | [-format] | [-geteditsize]
| COMMAND_OPTION | Description |
|---|---|
| -checkpoint [force] | Checkpoints the SecondaryNameNode if EditLog size >= fs.checkpoint.size. If force is used, checkpoint irrespective of EditLog size. |
| -format | Format the local storage during startup. |
| -geteditsize | Prints the number of uncheckpointed transactions on the NameNode. |