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https://issues.apache.org/jira/browse/HADOOP-2012?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12548797
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Konstantin Shvachko commented on HADOOP-2012:
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The question here is whether we would go with our current decision if we new it
will not be supported on windows?
If we let the balancer write a log type data (verified block #s) into a special
file "balancer.log" instead of modifying
meta-data files, will that be a problem? Looks like Eric already had a proposal
of scanning blocks in a predetermined
order. Should we reconsider this?
> Periodic verification at the Datanode
> -------------------------------------
>
> Key: HADOOP-2012
> URL: https://issues.apache.org/jira/browse/HADOOP-2012
> Project: Hadoop
> Issue Type: New Feature
> Components: dfs
> Reporter: Raghu Angadi
> Assignee: Raghu Angadi
> Fix For: 0.16.0
>
> Attachments: HADOOP-2012.patch, HADOOP-2012.patch, HADOOP-2012.patch,
> HADOOP-2012.patch
>
>
> Currently on-disk data corruption on data blocks is detected only when it is
> read by the client or by another datanode. These errors are detected much
> earlier if datanode can periodically verify the data checksums for the local
> blocks.
> Some of the issues to consider :
> - How should we check the blocks ( no more often than once every couple of
> weeks ?)
> - How do we keep track of when a block was last verfied ( there is a .meta
> file associcated with each lock ).
> - What action to take once a corruption is detected
> - Scanning should be done as a very low priority with rest of the datanode
> disk traffic in mind.
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