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https://issues.apache.org/jira/browse/HADOOP-4663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12674490#action_12674490
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dhruba borthakur commented on HADOOP-4663:
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An offline discussion with Hairong, Sanjay, Rob Chansler, Raghu and Konstantin
resulted in these observations. 'bbw" refers to "blocksBeingWritten" directory.
1. leave blocks in bbw directory even when data restarts. only when the block
is finalized (when user closes the block or lease recovery occurs), does the
block move to the real block directory.
2. first block report (following a datanode registration) sends all blocks
(including blocks in bbw)
3. the block report processing on namenode ignores blocks that are under
construction
4. lease recovery should verify crc of block before they get promoted from bbw
to real block directory
5. When lease recovery ocurs, the datanode should terminate writer-threads
before returning length of block
> Datanode should delete files under tmp when upgraded from 0.17
> --------------------------------------------------------------
>
> Key: HADOOP-4663
> URL: https://issues.apache.org/jira/browse/HADOOP-4663
> Project: Hadoop Core
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.18.0
> Reporter: Raghu Angadi
> Assignee: dhruba borthakur
> Priority: Blocker
> Fix For: 0.19.2
>
> Attachments: appendQuestions.txt, deleteTmp.patch, deleteTmp2.patch,
> deleteTmp_0.18.patch, handleTmp1.patch
>
>
> Before 0.18, when Datanode restarts, it deletes files under data-dir/tmp
> directory since these files are not valid anymore. But in 0.18 it moves these
> files to normal directory incorrectly making them valid blocks. One of the
> following would work :
> - remove the tmp files during upgrade, or
> - if the files under /tmp are in pre-18 format (i.e. no generation), delete
> them.
> Currently effect of this bug is that, these files end up failing block
> verification and eventually get deleted. But cause incorrect over-replication
> at the namenode before that.
> Also it looks like our policy regd treating files under tmp needs to be
> defined better. Right now there are probably one or two more bugs with it.
> Dhruba, please file them if you rememeber.
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