[HADOOP-7961] HA: fencing mechanism - ASF JIRA

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Details

Type: Sub-task
Status: Resolved
Priority: Major
Resolution: Fixed
Affects Version/s: None
Fix Version/s: HA Branch (HDFS-1623)
Component/s: ha
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Hadoop Flags:

Reviewed

Description

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.