[
https://issues.apache.org/jira/browse/ZOOKEEPER-261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15822481#comment-15822481
]
ASF GitHub Bot commented on ZOOKEEPER-261:
------------------------------------------
Github user hanm commented on the issue:
https://github.com/apache/zookeeper/pull/120
Right, it is committed, confirmed. I was only checking the apache mirror on
git (https://github.com/apache/zookeeper), instead of the apache git directly.
I suspect there is some infra issues on Apache (the JIRA was done
yesterday) which contributes to the bridging between various systems not
working as expected, leading to this PR not closed automatically.
> Reinitialized servers should not participate in leader election
> ---------------------------------------------------------------
>
> Key: ZOOKEEPER-261
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-261
> Project: ZooKeeper
> Issue Type: Improvement
> Components: leaderElection, quorum
> Reporter: Benjamin Reed
>
> A server that has lost its data should not participate in leader election
> until it has resynced with a leader. Our leader election algorithm and
> NEW_LEADER commit assumes that the followers voting on a leader have not lost
> any of their data. We should have a flag in the data directory saying whether
> or not the data is preserved so that the the flag will be cleared if the data
> is ever cleared.
> Here is the problematic scenario: you have have ensemble of machines A, B,
> and C. C is down. the last transaction seen by C is z. a transaction, z+1, is
> committed on A and B. Now there is a power outage. B's data gets
> reinitialized. when power comes back up, B and C comes up, but A does not. C
> will be elected leader and transaction z+1 is lost. (note, this can happen
> even if all three machines are up and C just responds quickly. in that case C
> would tell A to truncate z+1 from its log.) in theory we haven't violated our
> 2f+1 guarantee, since A is failed and B still hasn't recovered from failure,
> but it would be nice if when we don't have quorum that system stops working
> rather than works incorrectly if we lose quorum.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
