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HDFS-10894. Remove the redundant charactors for command -saveNamespace in HDFSCommands.md Contributed by Yiqun Lin.

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Brahma Reddy Battula 2016-09-23 19:11:02 +05:30
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hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md
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@ -402,7 +402,7 @@ Usage:
|:---- |:---- |
| `-report` `[-live]` `[-dead]` `[-decommissioning]` | 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. |
| `-safemode` enter\|leave\|get\|wait\|forceExit | 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. |
| `-saveNamespace` `\[-beforeShutdown\]` | 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. |
| `-saveNamespace` `[-beforeShutdown]` | 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. |
| `-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. |