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HDFS-14998. [SBN read] Update Observer Namenode doc for ZKFC after HDFS-14130. Contributed by Fei Hui.

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This commit is contained in:
Ayush Saxena 2019-12-06 23:04:09 +05:30
parent fccccc9703
commit 705b172b95
1 changed files with 9 additions and 7 deletions
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hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/ObserverNameNode.md
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@ -224,10 +224,10 @@ Observer NameNode, which transition it to the standby state.
**NOTE**: the feature for Observer NameNode to participate in failover **NOTE**: the feature for Observer NameNode to participate in failover
is not implemented yet. Therefore, as described in the next section, you is not implemented yet. Therefore, as described in the next section, you
should only use **transitionToObserver** to bring up an observer and put should only use **transitionToObserver** to bring up an observer. ZKFC
it outside the ZooKeeper controlled failover group. You should not use could be turned on the Observer NameNode, but it doesn't do anything when
**transitionToStandby** since the host for the Observer NameNode cannot the NameNode is in Observer state. ZKFC will participate in the election of
have ZKFC running. Active after the NameNode is transitioned to standby state.
### Deployment details ### Deployment details
@ -240,9 +240,11 @@ on the intensity of read requests and HA requirements.
Note that currently Observer NameNode doesn't integrate fully when Note that currently Observer NameNode doesn't integrate fully when
automatic failover is enabled. If the automatic failover is enabled. If the
**dfs.ha.automatic-failover.enabled** is turned on, you'll also need to **dfs.ha.automatic-failover.enabled** is turned on, the only benefit for
disable ZKFC on the namenode for observer. In addition to that, you'll running ZKFC on Observer NameNode is that it will automatically join election
also need to add **forcemanual** flag to the **transitionToObserver** of Active after you transition the NameNode to Standby. If this is not desired,
you can disable ZKFC on the Observer NameNode. In addition to that, you'll also
need to add **forcemanual** flag to the **transitionToObserver**
command: command:
haadmin -transitionToObserver -forcemanual haadmin -transitionToObserver -forcemanual