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https://issues.apache.org/jira/browse/ZOOKEEPER-2678?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15863783#comment-15863783
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ASF GitHub Bot commented on ZOOKEEPER-2678:
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Github user revans2 commented on the issue:
https://github.com/apache/zookeeper/pull/157
@rakeshadr If it makes you feel any better we have been running with an
older version of this patch in production for a while. We have used it as part
of a rolling upgrade at least 10 times in production where if it were not there
we would have had some very painful outages.
I have also manually tested it at least 50 times shooting the leader under
load (10,000 operations/second) on a 3.4 GB DB, watching it recover, and then
validating the integrity of the DB to be sure we didn't get any corruption.
> Large databases take a long time to regain a quorum
> ---------------------------------------------------
>
> Key: ZOOKEEPER-2678
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2678
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.4.9, 3.5.2
> Reporter: Robert Joseph Evans
> Assignee: Robert Joseph Evans
> Fix For: 3.6.0
>
>
> I know this is long but please here me out.
> I recently inherited a massive zookeeper ensemble. The snapshot is 3.4 GB on
> disk. Because of its massive size we have been running into a number of
> issues. There are lots of problems that we hope to fix with tuning GC etc,
> but the big one right now that is blocking us making a lot of progress on the
> rest of them is that when we lose a quorum because the leader left, for what
> ever reason, it can take well over 5 mins for a new quorum to be established.
> So we cannot tune the leader without risking downtime.
> We traced down where the time was being spent and found that each server was
> clearing the database so it would be read back in again before leader
> election even started. Then as part of the sync phase each server will write
> out a snapshot to checkpoint the progress it made as part of the sync.
> I will be putting up a patch shortly with some proposed changes in it.
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