hadoop-common-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Bikas Saha (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-8217) Edge case split-brain race in ZK-based auto-failover
Date Sat, 31 Mar 2012 00:09:27 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-8217?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13242874#comment-13242874

Bikas Saha commented on HADOOP-8217:

bq.4(failure case): if NN1.transitionToStandby() times out or fails, the non-graceful fencing
is initiated (same as in existing HA code for the last several months)

Can you please point me to the existing HA code for last several months? I thought we have
manual HA in which admin does fencing. 
> Edge case split-brain race in ZK-based auto-failover
> ----------------------------------------------------
>                 Key: HADOOP-8217
>                 URL: https://issues.apache.org/jira/browse/HADOOP-8217
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: auto-failover, ha
>    Affects Versions: 0.24.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>         Attachments: hadoop-8217-testcase.txt
> As discussed in HADOOP-8206, the current design for automatic failover has the following
> - ZKFC1 gets active lock
> - ZKFC1 is about to send transitionToActive() and machine freezes (eg GC pause + swapping)
> - ZKFC1 loses its ZK lock, ZKFC2 gets ZK lock
> - ZKFC2 calls transitionToStandby on NN1, and transitions NN2 to active
> - ZKFC1 wakes up from pause, calls transitionToActive(), now we have a bad situation
> This is rare, since it requires ZKFC1 to freeze longer than its ZK session timeout, but
worth fixing, since the results can be disastrous.

This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira


View raw message