namenode

Sergey Ostapov

Runs the NameNode.

The usage is as follows:

$ 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 <rollback |started> ] |
          [-importCheckpoint] |
          [-initializeSharedEdits] |
          [-bootstrapStandby [-force] [-nonInteractive] [-skipSharedEditsCheck] ] |
          [-recover [-force] ] |
          [-metadataVersion ]

Arguments
-backup	Starts the Backup node
-checkpoint	Starts a Checkpoint node
-format [-clusterid cid]	Formats the specified NameNode. It starts the NameNode, formats it and then shuts it down. Will throw `NameNodeFormatException` if the directory already exists and if reformatting is disabled for the cluster
-upgrade [-clusterid cid] [-renameReserved <k-v pairs>]	NameNode should be started with the `upgrade` option after the distribution of a new Arenadata Hadoop version
-upgradeOnly [-clusterid cid] [-renameReserved <k-v pairs>]	Upgrades the specified NameNode and then shuts it down
-rollback	Rolls back a NameNode to the previous version. This should be used after stopping the cluster and distributing the old Arenadata Hadoop version
-rollingUpgrade <rollback\|started>	When a rolling upgrade is in progress, the `-rollingUpgrade` NameNode startup option is used to specify various rolling upgrade options: `rollback`: restores the NameNode back to the pre-upgrade release and also reverts the user data back to the pre-upgrade state; `started`: specifies a rolling upgrade already started so that the NameNode should allow image directories with different layout versions during startup.
-importCheckpoint	Loads an image from a checkpoint directory and saves it into the current one. Checkpoint dir is read from property `dfs.namenode.checkpoint.dir`
-initializeSharedEdits	Formats a new shared edits dir and copies to available edit log segments so that the Standby NameNode can start up
-bootstrapStandby [-force] [-nonInteractive] [-skipSharedEditsCheck]	Allows a 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 described in the namenode -format command
-recover [-force]	Recovers lost metadata on a corrupt filesystem
-metadataVersion	Verifies that configured directories exist, then prints the metadata versions of the software and the image

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