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From "patrick white (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-6203) check other namenode's state before HAadmin transitionToActive
Date Tue, 08 Apr 2014 21:04:14 GMT
patrick white created HDFS-6203:

             Summary: check other namenode's state before HAadmin transitionToActive
                 Key: HDFS-6203
                 URL: https://issues.apache.org/jira/browse/HDFS-6203
             Project: Hadoop HDFS
          Issue Type: Improvement
          Components: ha
    Affects Versions: 2.3.0
            Reporter: patrick white

Current behavior is that the HAadmin -transitionToActive command will complete the transition
to Active even if the other namenode is already in Active state. This is not an allowed condition
and should be handled by fencing, however setting both namenode's active can happen accidentally
with relative ease, especially in a production environment when performing manual maintenance

If this situation does occur it is very serious and will likely cause data loss, or best case,
require a difficult recovery to avoid data loss.

This is requesting an enhancement to haadmin's -transitionToActive command, to have HAadmin
check the Active state of the other namenode before completing the transition. If the other
namenode is Active, then fail the request due to other nn already-active.

Not sure if there is a scenario where both namenode's being Active is valid or desired, but
to maintain functional compatibility a 'force' parameter could be added to  override this
check and allow previous behavior.

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