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https://issues.apache.org/jira/browse/HDFS-630?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12762511#action_12762511
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dhruba borthakur commented on HDFS-630:
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The code looks good. But as you might be knowing, only regression fixes go into
pre-existing release branches. We can target this fix for trunk. If you can
merge this path with hadoop trunk and resubmit your patch, that will be great.
Also, most patch submissions require an associated junit test. You can find
many existing junit tests in the src/test directory of the svn repository.
Thanks.
> In DFSOutputStream.nextBlockOutputStream(), the client can exclude specific
> datanodes when locating the next block.
> -------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-630
> URL: https://issues.apache.org/jira/browse/HDFS-630
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: hdfs client
> Affects Versions: 0.20.1, 0.21.0
> Reporter: Ruyue Ma
> Assignee: Ruyue Ma
> Priority: Minor
> Fix For: 0.21.0
>
> Attachments: HDFS-630.patch
>
>
> created from hdfs-200.
> If during a write, the dfsclient sees that a block replica location for a
> newly allocated block is not-connectable, it re-requests the NN to get a
> fresh set of replica locations of the block. It tries this
> dfs.client.block.write.retries times (default 3), sleeping 6 seconds between
> each retry ( see DFSClient.nextBlockOutputStream).
> This setting works well when you have a reasonable size cluster; if u have
> few datanodes in the cluster, every retry maybe pick the dead-datanode and
> the above logic bails out.
> Our solution: when getting block location from namenode, we give nn the
> excluded datanodes. The list of dead datanodes is only for one block
> allocation.
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