<li><ahref="#dfsadmin_with_ViewFsOverloadScheme">dfsadmin with ViewFsOverloadScheme</a></li></ul>
<section>
<h2><aname="Overview"></a>Overview</h2>
<p>All HDFS commands are invoked by the <code>bin/hdfs</code> script. Running the hdfs script without any arguments prints the description for all commands.</p>
<p>Hadoop has an option parsing framework that employs parsing generic options as well as running classes.</p>
<tableborder="0"class="bodyTable">
<thead>
<trclass="a">
<thalign="left"> COMMAND_OPTIONS </th>
<thalign="left"> Description </th></tr>
</thead><tbody>
<trclass="b">
<tdalign="left"> SHELL_OPTIONS </td>
<tdalign="left"> The common set of shell options. These are documented on the <ahref="../../hadoop-project-dist/hadoop-common/CommandsManual.html#Shell_Options">Commands Manual</a> page. </td></tr>
<trclass="a">
<tdalign="left"> GENERIC_OPTIONS </td>
<tdalign="left"> The common set of options supported by multiple commands. See the Hadoop <ahref="../../hadoop-project-dist/hadoop-common/CommandsManual.html#Generic_Options">Commands Manual</a> for more information. </td></tr>
<trclass="b">
<tdalign="left"> COMMAND_OPTIONS </td>
<tdalign="left"> Various commands with their options are described in the following sections. The commands have been grouped into <ahref="#User_Commands">User Commands</a> and <ahref="#Administration_Commands">Administration Commands</a>. </td></tr>
</tbody>
</table></section><section>
<h2><aname="User_Commands"></a>User Commands</h2>
<p>Commands useful for users of a hadoop cluster.</p><section>
<p>Prints the class path needed to get the Hadoop jar and the required libraries. If called without arguments, then prints the classpath set up by the command scripts, which is likely to contain wildcards in the classpath entries. Additional options print the classpath after wildcard expansion or write the classpath into the manifest of a jar file. The latter is useful in environments where wildcards cannot be used and the expanded classpath exceeds the maximum supported command line length.</p></section><section>
<p>Run a filesystem command on the file system supported in Hadoop. The various COMMAND_OPTIONS can be found at <ahref="../hadoop-common/FileSystemShell.html">File System Shell Guide</a>.</p></section><section>
<tdalign="left"> Include snapshot data if the given path indicates a snapshottable directory or there are snapshottable directories under it. </td></tr>
<p>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.</p></section><section>
<tdalign="left"> 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) </td></tr>
<tdalign="left"> 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). </td></tr>
</tbody>
</table>
<p>Hadoop offline edits viewer. See <ahref="./HdfsEditsViewer.html">Offline Edits Viewer Guide</a> for more info.</p></section></section><section>
<h3><aname="oiv"></a><code>oiv</code></h3>
<p>Usage: <code>hdfs oiv [OPTIONS] -i INPUT_FILE</code></p><section>
<h4><aname="Required_command_line_arguments:"></a>Required command line arguments:</h4>
<tdalign="left"> Specify the output filename, if the specified output processor generates one. If the specified file already exists, it is silently overwritten. (output to stdout by default) If the input file is an XML file, it also creates an <outputFile>.md5. </td></tr>
<tdalign="left"> Specify the image processor to apply against the image file. Currently valid options are <code>Web</code> (default), <code>XML</code>, <code>Delimited</code>, <code>FileDistribution</code> and <code>ReverseXML</code>. </td></tr>
<tdalign="left"> Specify the range [0, maxSize] of file sizes to be analyzed in bytes (128GB by default). This option is used with FileDistribution processor. </td></tr>
<tdalign="left"> Specify the granularity of the distribution in bytes (2MB by default). This option is used with FileDistribution processor. </td></tr>
<trclass="a">
<tdalign="left"><code>-format</code></td>
<tdalign="left"> Format the output result in a human-readable fashion rather than a number of bytes. (false by default). This option is used with FileDistribution processor. </td></tr>
<tdalign="left"> Use temporary dir to cache intermediate result to generate Delimited outputs. If not set, Delimited processor constructs the namespace in memory before outputting text. </td></tr>
<tdalign="left"> Display the tool usage and help information and exit. </td></tr>
</tbody>
</table>
<p>Hadoop Offline Image Viewer for image files in Hadoop 2.4 or up. See <ahref="./HdfsImageViewer.html">Offline Image Viewer Guide</a> for more info.</p></section></section><section>
<tdalign="left"> Specify the output filename, if the specified output processor generates one. If the specified file already exists, it is silently overwritten. </td></tr>
</tbody>
</table><section>
<h4><aname="Optional_command_line_arguments:"></a>Optional command line arguments:</h4>
<tdalign="left"> Specify the image processor to apply against the image file. Valid options are Ls (default), XML, Delimited, Indented, FileDistribution and NameDistribution. </td></tr>
<tdalign="left"> Specify the range [0, maxSize] of file sizes to be analyzed in bytes (128GB by default). This option is used with FileDistribution processor. </td></tr>
<tdalign="left"> Specify the granularity of the distribution in bytes (2MB by default). This option is used with FileDistribution processor. </td></tr>
<trclass="a">
<tdalign="left"><code>-format</code></td>
<tdalign="left"> Format the output result in a human-readable fashion rather than a number of bytes. (false by default). This option is used with FileDistribution processor. </td></tr>
<trclass="b">
<tdalign="left"><code>-skipBlocks</code></td>
<tdalign="left"> Do not enumerate individual blocks within files. This may save processing time and outfile file space on namespaces with very large files. The Ls processor reads the blocks to correctly determine file sizes and ignores this option. </td></tr>
<trclass="a">
<tdalign="left"><code>-printToScreen</code></td>
<tdalign="left"> Pipe output of processor to console as well as specified file. On extremely large namespaces, this may increase processing time by an order of magnitude. </td></tr>
<tdalign="left"> When used in conjunction with the Delimited processor, replaces the default tab delimiter with the string specified by <i>arg</i>. </td></tr>
<tdalign="left"> Display the tool usage and help information and exit. </td></tr>
</tbody>
</table>
<p>Hadoop offline image viewer for older versions of Hadoop. See <ahref="./HdfsImageViewer.html#oiv_legacy_Command">oiv_legacy Command</a> for more info.</p></section></section><section>
<p>Determine the difference between HDFS snapshots. See the <ahref="./HdfsSnapshots.html#Get_Snapshots_Difference_Report">HDFS Snapshot Documentation</a> for more information.</p></section><section>
<tdalign="left"><code>datanode</code> (default): Cluster is balanced if each datanode is balanced.<br/><code>blockpool</code>: Cluster is balanced if each block pool in each datanode is balanced. </td></tr>
<tdalign="left"> Whether to run the balancer during an ongoing HDFS upgrade. This is usually not desired since it will not affect used space on over-utilized machines. </td></tr>
<trclass="b">
<tdalign="left"><code>-asService</code></td>
<tdalign="left"> Run Balancer as a long running service. </td></tr>
<tdalign="left"> Display the tool usage and help information and exit. </td></tr>
</tbody>
</table>
<p>Runs a cluster balancing utility. An administrator can simply press Ctrl-C to stop the rebalancing process. See <ahref="./HdfsUserGuide.html#Balancer">Balancer</a> for more details.</p>
<p>Note that the <code>blockpool</code> policy is stricter than the <code>datanode</code> policy.</p>
<p>Besides the above command options, a pinning feature is introduced starting from 2.7.0 to prevent certain replicas from getting moved by balancer/mover. This pinning feature is disabled by default, and can be enabled by configuration property “dfs.datanode.block-pinning.enabled”. When enabled, this feature only affects blocks that are written to favored nodes specified in the create() call. This feature is useful when we want to maintain the data locality, for applications such as HBase regionserver.</p>
<p>If you want to run Balancer as a long-running service, please start Balancer using <code>-asService</code> parameter with daemon-mode. You can do this by using the following command: <code>hdfs --daemon start balancer -asService</code>, or just use sbin/start-balancer.sh script with parameter <code>-asService</code>.</p></section><section>
<p>See the <ahref="./CentralizedCacheManagement.html#cacheadmin_command-line_interface">HDFS Cache Administration Documentation</a> for more information.</p></section><section>
<p>See the <ahref="./TransparentEncryption.html#crypto_command-line_interface">HDFS Transparent Encryption Documentation</a> for more information.</p></section><section>
<tdalign="left"> Normal datanode startup (default). </td></tr>
<trclass="a">
<tdalign="left"><code>-rollback</code></td>
<tdalign="left"> Rollback the datanode to the previous version. This should be used after stopping the datanode and distributing the old hadoop version. </td></tr>
<tdalign="left"> Reports basic filesystem information and statistics, The dfs usage can be different from “du” usage, because it measures raw space used by replication, checksums, snapshots and etc. on all the DNs. Optional flags may be used to filter the list of displayed DataNodes. Filters are either based on the DN state (e.g. live, dead, decommissioning) or the nature of the DN (e.g. slow nodes - nodes with higher latency than their peers). </td></tr>
<tdalign="left"> Safe mode maintenance command. Safe mode is a Namenode state in which it <br/>1. does not accept changes to the name space (read-only) <br/>2. does not replicate or delete blocks. <br/>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. If Namenode detects any anomaly then it will linger in safe mode till that issue is resolved. If that anomaly is the consequence of a deliberate action, then administrator can use -safemode forceExit to exit safe mode. The cases where forceExit may be required are<br/> 1. Namenode metadata is not consistent. If Namenode detects that metadata has been modified out of band and can cause data loss, then Namenode will enter forceExit state. At that point user can either restart Namenode with correct metadata files or forceExit (if data loss is acceptable).<br/>2. Rollback causes metadata to be replaced and rarely it can trigger safe mode forceExit state in Namenode. In that case you may proceed by issuing -safemode forceExit.<br/> Safe mode can also be entered manually, but then it can only be turned off manually as well. </td></tr>
<tdalign="left"> Save current namespace into storage directories and reset edits log. Requires safe mode. If the “beforeShutdown” option is given, the NameNode does a checkpoint if and only if no checkpoint has been done during a time window (a configurable number of checkpoint periods). This is usually used before shutting down the NameNode to prevent potential fsimage/editlog corruption. </td></tr>
<trclass="a">
<tdalign="left"><code>-rollEdits</code></td>
<tdalign="left"> Rolls the edit log on the active NameNode. </td></tr>
<tdalign="left"> 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. </td></tr>
<trclass="a">
<tdalign="left"><code>-refreshNodes</code></td>
<tdalign="left"> 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. </td></tr>
<tdalign="left"> Finalize upgrade of HDFS. Datanodes delete their previous version working directories, followed by Namenode doing the same. This completes the upgrade process. </td></tr>
<tdalign="left"> Triggers a runtime-refresh of the resource specified by <key> on <host:ipc_port>. All other args after are sent to the host. </td></tr>
<tdalign="left"> Starts reconfiguration or gets the status of an ongoing reconfiguration, or gets a list of reconfigurable properties. The second parameter specifies the node type. The third parameter specifies host address. For start or status, datanode supports livenodes as third parameter, which will start or retrieve reconfiguration on all live datanodes. </td></tr>
<trclass="a">
<tdalign="left"><code>-printTopology</code></td>
<tdalign="left"> Print a tree of the racks and their nodes as reported by the Namenode </td></tr>
<tdalign="left"> For the given datanode, reloads the configuration files, stops serving the removed block-pools and starts serving new block-pools. </td></tr>
<tdalign="left"> 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. </td></tr>
<trclass="a">
<tdalign="left"><code>-setBalancerBandwidth</code><bandwidth in bytes per second></td>
<tdalign="left"> 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.datanode.balance.bandwidthPerSec parameter. NOTE: The new value is not persistent on the DataNode. </td></tr>
<tdalign="left"> Get the network bandwidth(in bytes per second) for the given datanode. This is the maximum network bandwidth used by the datanode during HDFS block balancing.</td></tr>
<tdalign="left"> Allowing snapshots of a directory to be created. If the operation completes successfully, the directory becomes snapshottable. See the <ahref="./HdfsSnapshots.html">HDFS Snapshot Documentation</a> for more information. </td></tr>
<tdalign="left"> Disallowing snapshots of a directory to be created. All snapshots of the directory must be deleted before disallowing snapshots. See the <ahref="./HdfsSnapshots.html">HDFS Snapshot Documentation</a> for more information. </td></tr>
<tdalign="left"> Submit a shutdown request for the given datanode. See <ahref="./HdfsRollingUpgrade.html#dfsadmin_-shutdownDatanode">Rolling Upgrade document</a> for the detail. </td></tr>
<tdalign="left"> Make the datanode evict all clients that are writing a block. This is useful if decommissioning is hung due to slow writers. </td></tr>
<tdalign="left"> Get the information about the given datanode. See <ahref="./HdfsRollingUpgrade.html#dfsadmin_-getDatanodeInfo">Rolling Upgrade document</a> for the detail. </td></tr>
<tdalign="left"> Save Namenode’s primary data structures to <i>filename</i> in the directory specified by hadoop.log.dir property. <i>filename</i> is overwritten if it exists. <i>filename</i> will contain one line for each of the following<br/>1. Datanodes heart beating with Namenode<br/>2. Blocks waiting to be replicated<br/>3. Blocks currently being replicated<br/>4. Blocks waiting to be deleted </td></tr>
<tdalign="left"> Trigger a block report for the given datanode. If ‘incremental’ is specified, it will be otherwise, it will be a full block report. If ‘-namenode <namenode_host:ipc_port>’ is given, it only sends block report to a specified namenode. </td></tr>
<tdalign="left"> List all open files currently managed by the NameNode along with client name and client machine accessing them. Open files list will be filtered by given type and path. Add -blockingDecommission option if you only want to list open files that are blocking the DataNode decommissioning. </td></tr>
<trclass="b">
<tdalign="left"><code>-help</code> [cmd] </td>
<tdalign="left"> Displays help for the given command or all commands if none is specified. </td></tr>
</tbody>
</table>
<p>Runs a HDFS dfsadmin client.</p></section><section>
<tdalign="left"> Set storage type quota for specified path. See <ahref="./HdfsQuotaAdminGuide.html">HDFS Quotas Guide</a> for the quota detail. </td></tr>
<tdalign="left"> Clear storage type quota of given mount point. See <ahref="./HdfsQuotaAdminGuide.html">HDFS Quotas Guide</a> for the quota detail. </td></tr>
<tdalign="left"> Manually set the Router entering or leaving safe mode. The option <i>get</i> will be used for verifying if the Router is in safe mode state. </td></tr>
<tdalign="left"> To trigger a runtime-refresh of the resource specified by <key> on <host:ipc_port>. For example, to enable white list checking, we just need to send a refresh command other than restart the router server. </td></tr>
<tdalign="left"> Reload the call queue from config for Router. </td></tr>
</tbody>
</table>
<p>The commands for managing Router-based federation. See <ahref="../hadoop-hdfs-rbf/HDFSRouterFederation.html#Mount_table_management">Mount table management</a> for more info.</p></section><section>
<tdalign="left"> Set a specified ErasureCoding policy to a directory</td></tr>
<trclass="a">
<tdalign="left">-getPolicy</td>
<tdalign="left"> Get ErasureCoding policy information about a specified path</td></tr>
<trclass="b">
<tdalign="left">-unsetPolicy</td>
<tdalign="left"> Unset an ErasureCoding policy set by a previous call to “setPolicy” on a directory </td></tr>
<trclass="a">
<tdalign="left">-listPolicies</td>
<tdalign="left"> Lists all supported ErasureCoding policies</td></tr>
<trclass="b">
<tdalign="left">-addPolicies</td>
<tdalign="left"> Add a list of erasure coding policies</td></tr>
<trclass="a">
<tdalign="left">-listCodecs</td>
<tdalign="left"> Get the list of supported erasure coding codecs and coders in system</td></tr>
<trclass="b">
<tdalign="left">-enablePolicy</td>
<tdalign="left"> Enable an ErasureCoding policy in system</td></tr>
<trclass="a">
<tdalign="left">-disablePolicy</td>
<tdalign="left"> Disable an ErasureCoding policy in system</td></tr>
<trclass="b">
<tdalign="left">-removePolicy</td>
<tdalign="left"> Remove an ErasureCoding policy from system</td></tr>
<trclass="a">
<tdalign="left">-verifyClusterSetup</td>
<tdalign="left"> Verify if the cluster setup can support a list of erasure coding policies</td></tr>
</tbody>
</table>
<p>Runs the ErasureCoding CLI. See <ahref="./HDFSErasureCoding.html#Administrative_commands">HDFS ErasureCoding</a> for more information on this command.</p></section><section>
<tdalign="left"> transition the state of the given NameNode to Observer (Warning: No fencing is done) </td></tr>
<trclass="a">
<tdalign="left"><code>-help</code> [cmd] </td>
<tdalign="left"> Displays help for the given command or all commands if none is specified. </td></tr>
</tbody>
</table>
<p>See <ahref="./HDFSHighAvailabilityWithNFS.html#Administrative_commands">HDFS HA with NFS</a> or <ahref="./HDFSHighAvailabilityWithQJM.html#Administrative_commands">HDFS HA with QJM</a> for more information on this command.</p></section><section>
<p>This command starts a journalnode for use with <ahref="./HDFSHighAvailabilityWithQJM.html#Administrative_commands">HDFS HA with QJM</a>.</p></section><section>
<tdalign="left"> Specify a space separated list of HDFS files/dirs to migrate. </td></tr>
</tbody>
</table>
<p>Runs the data migration utility. See <ahref="./ArchivalStorage.html#Mover_-_A_New_Data_Migration_Tool">Mover</a> for more details.</p>
<p>Note that, when both -p and -f options are omitted, the default path is the root directory.</p>
<p>In addition, a pinning feature is introduced starting from 2.7.0 to prevent certain replicas from getting moved by balancer/mover. This pinning feature is disabled by default, and can be enabled by configuration property “dfs.datanode.block-pinning.enabled”. When enabled, this feature only affects blocks that are written to favored nodes specified in the create() call. This feature is useful when we want to maintain the data locality, for applications such as HBase regionserver.</p></section><section>
<tdalign="left"> Formats the specified NameNode. It starts the NameNode, formats it and then shut it down. Will throw NameNodeFormatException if name dir already exist and if reformat is disabled for cluster. </td></tr>
<tdalign="left"> Upgrade the specified NameNode and then shutdown it. </td></tr>
<trclass="a">
<tdalign="left"><code>-rollback</code></td>
<tdalign="left"> Rollback the NameNode to the previous version. This should be used after stopping the cluster and distributing the old Hadoop version. </td></tr>
<tdalign="left"> Loads image from a checkpoint directory and save it into the current one. Checkpoint dir is read from property dfs.namenode.checkpoint.dir </td></tr>
<tdalign="left"> 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. The option -force or -nonInteractive has the same meaning as that described in namenode -format command. -skipSharedEditsCheck option skips edits check which ensures that we have enough edits already in the shared directory to start up from the last checkpoint on the active. </td></tr>
<tdalign="left"> Recover lost metadata on a corrupt filesystem. See <ahref="./HdfsUserGuide.html#Recovery_Mode">HDFS User Guide</a> for the detail. </td></tr>
<tdalign="left"> Verify that configured directories exist, then print the metadata versions of the software and the image. </td></tr>
</tbody>
</table>
<p>Runs the namenode. More info about the upgrade and rollback is at <ahref="./HdfsUserGuide.html#Upgrade_and_Rollback">Upgrade Rollback</a>.</p></section><section>
<h3><aname="nfs3"></a><code>nfs3</code></h3>
<p>Usage: <code>hdfs nfs3</code></p>
<p>This command starts the NFS3 gateway for use with the <ahref="./HdfsNfsGateway.html#Start_and_stop_NFS_gateway_service">HDFS NFS3 Service</a>.</p></section><section>
<p>This command starts the RPC portmap for use with the <ahref="./HdfsNfsGateway.html#Start_and_stop_NFS_gateway_service">HDFS NFS3 Service</a>.</p></section><section>
<tdalign="left"> Checkpoints the SecondaryNameNode if EditLog size >= fs.checkpoint.size. If <code>force</code> is used, checkpoint irrespective of EditLog size. </td></tr>
<trclass="a">
<tdalign="left"><code>-format</code></td>
<tdalign="left"> Format the local storage during startup. </td></tr>
<trclass="b">
<tdalign="left"><code>-geteditsize</code></td>
<tdalign="left"> Prints the number of uncheckpointed transactions on the NameNode. </td></tr>
</tbody>
</table>
<p>Runs the HDFS secondary namenode. See <ahref="./HdfsUserGuide.html#Secondary_NameNode">Secondary Namenode</a> for more info.</p></section><section>
<p>Lists out all/Gets/sets/unsets storage policies. See the <ahref="./ArchivalStorage.html">HDFS Storage Policy Documentation</a> for more information.</p></section><section>
<tdalign="left"> Format the Zookeeper instance. -force: formats the znode if the znode exists. -nonInteractive: formats the znode aborts if the znode exists, unless -force option is specified. </td></tr>
<trclass="a">
<tdalign="left"><code>-h</code></td>
<tdalign="left"> Display help </td></tr>
</tbody>
</table>
<p>This command starts a Zookeeper Failover Controller process for use with <ahref="./HDFSHighAvailabilityWithQJM.html#Administrative_commands">HDFS HA with QJM</a>.</p></section></section><section>
<tdalign="left"> Absolute path for the metadata file on the local file system of the data node. </td></tr>
</tbody>
</table>
<p>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.</p></section><section>
<tdalign="left"> Absolute path for the output metadata file to store the checksum computation result from the block file. </td></tr>
</tbody>
</table>
<p>Compute HDFS metadata from block files. If a block file is specified, we will compute the checksums from the block file, and save it to the specified output metadata file.</p>
<p><b>NOTE</b>: Use at your own risk! If the block file is corrupt and you overwrite it’s meta file, it will show up as ‘good’ in HDFS, but you can’t read the data. Only use as a last measure, and when you are 100% certain the block file is good.</p></section><section>
<tdalign="left"> HDFS EC file to be verified. </td></tr>
</tbody>
</table>
<p>Verify the correctness of erasure coding on an erasure coded file.</p></section></section><section>
<h2><aname="dfsadmin_with_ViewFsOverloadScheme"></a>dfsadmin with ViewFsOverloadScheme</h2>
<p>Usage: <code>hdfs dfsadmin -fs <child fs mount link URI><dfsadmin command options></code></p>
<tableborder="0"class="bodyTable">
<thead>
<trclass="a">
<thalign="left"> COMMAND_OPTION </th>
<thalign="left"> Description </th></tr>
</thead><tbody>
<trclass="b">
<tdalign="left"><code>-fs</code><i>child fs mount link URI</i></td>
<tdalign="left"> Its a logical mount link path to child file system in ViewFS world. This uri typically formed as src mount link prefixed with fs.defaultFS. Please note, this is not an actual child file system uri, instead its a logical mount link uri pointing to actual child file system</td></tr>
<p>In ViewFsOverloadScheme, we may have multiple child file systems as mount point mappings as shown in <ahref="./ViewFsOverloadScheme.html">ViewFsOverloadScheme Guide</a>. Here -fs option is an optional generic parameter supported by dfsadmin. When users want to execute commands on one of the child file system, they need to pass that file system mount mapping link uri to -fs option. Let’s take an example mount link configuration and dfsadmin command below.</p>
mount link mapping: hdfs://MyCluster1/user --> hdfs://MyCluster2/user
mount link path: /user
mount link uri: hdfs://MyCluster1/user
mount target uri for /user: hdfs://MyCluster2/user -->
</property>
</pre></div></div>
<p>If user wants to talk to <code>hdfs://MyCluster2/</code>, then they can pass -fs option (<code>-fs hdfs://MyCluster1/user</code>) Since /user was mapped to a cluster <code>hdfs://MyCluster2/user</code>, dfsadmin resolve the passed (<code>-fs hdfs://MyCluster1/user</code>) to target fs (<code>hdfs://MyCluster2/user</code>). This way users can get the access to all hdfs child file systems in ViewFsOverloadScheme. If there is no <code>-fs</code> option provided, then it will try to connect to the configured fs.defaultFS cluster if a cluster running with the fs.defaultFS uri.</p></section>
