[
https://issues.apache.org/jira/browse/HDFS-2179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13079539#comment-13079539
]
Suresh Srinivas commented on HDFS-2179:
---------------------------------------
My feeling is that this is not NN specific. Whether MR uses it or not, doing it
in common gets the abstractions right.
> HA: namenode fencing mechanism
> ------------------------------
>
> Key: HDFS-2179
> URL: https://issues.apache.org/jira/browse/HDFS-2179
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: name-node
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: HA branch (HDFS-1623)
>
> Attachments: hdfs-2179.txt, hdfs-2179.txt, hdfs-2179.txt
>
>
> In an HA cluster, when there are two NNs, the invariant that only one NN is
> active at a time has to be preserved in order to prevent "split brain
> syndrome." Thus, when a standby NN is transition to "active" state during a
> failover, it needs to somehow _fence_ the formerly active NN to ensure that
> it can no longer perform edits. This JIRA is to discuss and implement NN
> fencing.
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
