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https://issues.apache.org/jira/browse/HDFS-4754?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nicolas Liochon updated HDFS-4754:
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Status: Patch Available (was: Open)
> Add an API in the namenode to mark a datanode as stale
> ------------------------------------------------------
>
> Key: HDFS-4754
> URL: https://issues.apache.org/jira/browse/HDFS-4754
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client, namenode
> Reporter: Nicolas Liochon
> Assignee: Nicolas Liochon
> Priority: Critical
> Attachments: 4754.v1.patch, 4754.v2.patch, 4754.v4.patch
>
>
> There is a detection of the stale datanodes in HDFS since HDFS-3703, with a
> timeout, defaulted to 30s.
> There are two reasons to add an API to mark a node as stale even if the
> timeout is not yet reached:
> 1) ZooKeeper can detect that a client is dead at any moment. So, for HBase,
> we sometimes start the recovery before a node is marked staled. (even with
> reasonable settings as: stale: 20s; HBase ZK timeout: 30s
> 2) Some third parties could detect that a node is dead before the timeout,
> hence saving us the cost of retrying. An example or such hw is Arista,
> presented here by [~tsuna]
> http://tsunanet.net/~tsuna/fsf-hbase-meetup-april13.pdf, and confirmed in
> HBASE-6290.
> As usual, even if the node is dead it can comeback before the 10 minutes
> limit. So I would propose to set a timebound. The API would be
> namenode.markStale(String ipAddress, int port, long durationInMs);
> After durationInMs, the namenode would again rely only on its heartbeat to
> decide.
> Thoughts?
> If there is no objections, and if nobody in the hdfs dev team has the time to
> spend some time on it, I will give it a try for branch 2 & 3.
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