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Posted to dev@zookeeper.apache.org by "Brian Nixon (JIRA)" <ji...@apache.org> on 2019/01/08 01:16:00 UTC
[jira] [Commented] (ZOOKEEPER-3231) Purge task may lost data when
we have many invalid snapshots.
[ https://issues.apache.org/jira/browse/ZOOKEEPER-3231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16736548#comment-16736548 ]
Brian Nixon commented on ZOOKEEPER-3231:
----------------------------------------
It might also make sense to more aggressively delete invalid snapshots (in the mode of ZOOKEEPER-3082). If its straightforward to identify and purge such files then we won't have to worry about deleting valid snapshots in order to preserve invalid snapshots.
> Purge task may lost data when we have many invalid snapshots.
> --------------------------------------------------------------
>
> Key: ZOOKEEPER-3231
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3231
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.5.4, 3.4.13
> Reporter: Jiafu Jiang
> Priority: Major
>
> I read the ZooKeeper source code, and I find the purge task use FileTxnSnapLog#findNRecentSnapshots to find snapshots, but the method does not check whether the snapshots are valid.
> Consider a worse case, a ZooKeeper server may have many invalid snapshots, and when a purge task begins, it will use the zxid in the last snapshot's name to purge old snapshots and transaction logs, then we may lost data.
> I think we should use FileSnap#findNValidSnapshots(int) instead of FileSnap#findNRecentSnapshots in FileTxnSnapLog#findNRecentSnapshots, but I am not sure.
>
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