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https://issues.apache.org/jira/browse/ZOOKEEPER-1453?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13412448#comment-13412448
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Bill Bridge commented on ZOOKEEPER-1453:
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I am not up to speed on ZooKeeper terminology so I am guessing that the
"sentinel iirc" is the 0x42 (one of my favorite constants) at the end of each
record. I see that in Util.readTxnBytes it is validated to be 'B' (aka 0x42)
and the record is considered partial if it is wrong. This will certainly catch
a partial record.
Is there any way it could legitimately be anything other than 0x00 or 0x42? If
not, then it would be marginally more robust to consider it partial only if it
is 0x00, and corrupt if not 0x42. This could only happen if something outside
of Zookeeper damaged the log after it was written. Once the head DBA (DataBase
Administrator) from Amazon said to me "Sometimes blocks just go bad". Amazon
has a lot of blocks.
> corrupted logs may not be correctly identified by FileTxnIterator
> -----------------------------------------------------------------
>
> Key: ZOOKEEPER-1453
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1453
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.3.3
> Reporter: Patrick Hunt
> Priority: Critical
> Attachments: 10.10.5.123-withPath1489.tar.gz, 10.10.5.123.tar.gz,
> 10.10.5.42-withPath1489.tar.gz, 10.10.5.42.tar.gz,
> 10.10.5.44-withPath1489.tar.gz, 10.10.5.44.tar.gz
>
>
> See ZOOKEEPER-1449 for background on this issue. The main problem is that
> during server recovery
> org.apache.zookeeper.server.persistence.FileTxnLog.FileTxnIterator.next()
> does not indicate if the available logs are valid or not. In some cases (say
> a truncated record and a single txnlog in the datadir) we will not detect
> that the file is corrupt, vs reaching the end of the file.
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