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https://issues.apache.org/jira/browse/HADOOP-4663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12663850#action_12663850
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dhruba borthakur commented on HADOOP-4663:
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I had an offline discussion with Sanjay, Rob Chansler, Nicholas and partly with
Konstantin. Here is the summary:
This JIRA will go into 0.19. (For 0.18.3, the equivalent work will be done via
HADOOP-4997).
The proposal is that blocks that are created by client-writes be created in the
"blocks_being_written" directory whereas blocks created by replication requests
be created in "blocks_being_replicated" directory. On datanode restarts, the
blocks in the "tmp" directory and "blocks_being_replicated" directory are
deleted whereas the blocks in "blocks_being_written" directory are recovered
and promoted to the real block directory.
> 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: 0.18.3
>
> Attachments: deleteTmp.patch, deleteTmp2.patch, deleteTmp_0.18.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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