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https://issues.apache.org/jira/browse/ZOOKEEPER-2574?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15675807#comment-15675807
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Rakesh R commented on ZOOKEEPER-2574:
-------------------------------------
How about keeping only one jira open and close the other one. That way, we will
try to converge the discussions into one place. I'm OK to close any one of
these two jira issues:-)
Could you please look at [my previous
comment|https://issues.apache.org/jira/browse/ZOOKEEPER-2574?focusedCommentId=15662873&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15662873]
and do necessary src & test code merge from ZK-2420. Appreciate creating a
pull request for the same. Thanks!
> PurgeTxnLog can inadvertently delete required txn log files
> -----------------------------------------------------------
>
> Key: ZOOKEEPER-2574
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2574
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.4.7, 3.4.8, 3.5.0, 3.5.1, 3.5.2
> Environment: Zookeeper 3.4.8, standalone, and 3-server quorum
> Reporter: Abhishek Rai
> Assignee: Abhishek Rai
> Fix For: 3.4.10, 3.5.3
>
> Attachments: ZOOKEEPER-2574.2.patch, ZOOKEEPER-2574.3.patch,
> ZOOKEEPER-2574.4.patch, ZOOKEEPER-2574.5.patch, ZOOKEEPER-2574.6.patch,
> ZOOKEEPER-2574.patch
>
>
> As part of the fix for ZOOKEEPER-1797, the call to
> FileTxnSnapLog.getSnapshotLogs() was removed from PurgeTxnLog.java. As a
> result, some old-looking but required txn log files can be deleted, resulting
> in data corruption or loss.
> For example, consider the following:
> 1. Configuration:
> autopurge.snapRetainCount=3
> 2. Following files exist:
> log.100 spans transactions from zxid=100 till zxid=140 (inclusive)
> snapshot.110 - snapshot as of zxid=110
> snapshot.120 - snapshot as of zxid=120
> snapshot.130 - snapshot as of zxid=130
> Above scenario is possible when snapshotting has happened multiple times but
> without accompanying log rollover, which is possible if the server was
> running as a learner.
> 3. PurgeTxnLog retains all snapshots but deletes log.100 because its zxid is
> older than the zxid of the oldest snapshot (110). This results in loss of
> transactions in the range 131-140.
> Before the fix for ZOOKEEPER-1797, this was avoided by the call to
> FileTxnSnapLog.getSnapshotLogs() which finds and retains the newest txn log
> file with starting zxid < oldest retained snapshot's highest zxid.
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