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https://issues.apache.org/jira/browse/HADOOP-3184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12602948#action_12602948
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Hemanth Yamijala commented on HADOOP-3184:
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bq. I presume you mean in the case where some machines failed, but the cluster
eventually came up, right ? Because otherwise, we do print a report on the
command line for the users that the hodring on this machine failed due to this
reason. The services folks could then check the ringmaster log to see what
other machines failed.
In an offline conversation I had with Mahadev, I actually found that he had
meant the latter, which is supported. So, all is good. The utility of the other
feature remains, though it can be done as an enhancement at a later state.
> HOD gracefully exclude "bad" nodes during ring formation
> --------------------------------------------------------
>
> Key: HADOOP-3184
> URL: https://issues.apache.org/jira/browse/HADOOP-3184
> Project: Hadoop Core
> Issue Type: Improvement
> Components: contrib/hod
> Reporter: Marco Nicosia
> Assignee: Hemanth Yamijala
> Fix For: 0.18.0
>
> Attachments: 3184.1.patch, 3184.2.patch
>
>
> HOD clusters sometimes fail to allocate due to a single "bad" node. During
> ring formation, the entire ring should not be dependent upon every single
> node being good. Instead, it should either exclude any ring member that does
> not adequately join the ring in a specified amount of time.
> This is a frequent HOD user issue (although not directly caused by HOD).
> Examples of bad nodes: Missing java, incorrect version of HOD or Hadoop,
> local name-cache corrupt, slow network links, drives just beginning to fail,
> etc.
> Many of these conditions are known, and we can monitor for those separately,
> but this enhancement would shield users from unknown failure conditions that
> we haven't yet anticipated. This way, a user will get a cluster, instead of
> hanging indefinitely.
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