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https://issues.apache.org/jira/browse/HDFS-2981?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13213177#comment-13213177
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Tsz Wo (Nicholas), SZE commented on HDFS-2981:
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Hi Todd,
Enabling the feature does not mean that re-transferring a block when a node in
the pipeline fail. There is another conf property,
dfs.client.block.write.replace-datanode-on-failure.policy, for configuring the
policy. The default is
{noformat}
DEFAULT:
Let r be the replication number.
Let n be the number of existing datanodes.
Add a new datanode only if r is greater than or equal to 3 and either
(1) floor(r/2) is greater than or equal to n; or
(2) r is greater than n and the block is hflushed/appended.
{noformat}
Also, individual applications can set the policy to NEVER if it is desirable.
> The default value of
> dfs.client.block.write.replace-datanode-on-failure.enable should be true
> ---------------------------------------------------------------------------------------------
>
> Key: HDFS-2981
> URL: https://issues.apache.org/jira/browse/HDFS-2981
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Tsz Wo (Nicholas), SZE
> Attachments: h2981_20120221.patch
>
>
> There was a typo earlier in the default value of
> dfs.client.block.write.replace-datanode-on-failure.enable. Then, HDFS-2944
> changed from "ture" to "false". It should be changed to "true".
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