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https://issues.apache.org/jira/browse/HDFS-5016?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13715301#comment-13715301
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Kihwal Lee commented on HDFS-5016:
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We need to guarantee that no unintended data modification occurs after block
recoveries. If a writer could not be stopped right away, either 1) it has to
stop writing when it unblocks, or 2) the block shouldn't be considered as
recovered.
I think Suresh is saying 1) will happen and Nicholas is saying 2) will be
safer. I agree with Suresh for this particular scenario, but am not 100% sure
about all possible cases. E.g. if a writer is in the middle of slow disk write,
it can continue to write. As a result, data on disk can get modified after
successful recoverRbw(). I would prefer failing block recovery after timeout.
> Heartbeating thread blocks under some failure conditions leading to loss of
> datanodes
> -------------------------------------------------------------------------------------
>
> Key: HDFS-5016
> URL: https://issues.apache.org/jira/browse/HDFS-5016
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Devaraj Das
> Assignee: Suresh Srinivas
> Priority: Blocker
> Fix For: 2.1.0-beta
>
> Attachments: HDFS-5016.patch, jstack1.txt
>
>
> In the testing of some failure scenarios for HBase MTTR, we have been
> simulating node failures via firewalling of nodes (where all communication
> ports would be firewalled except ssh's port). We have noticed that when a
> (data)node is firewalled, we lose certain other datanodes - those that were
> involved in some communication with the firewalled node before the latter was
> firewalled. Will attach jstack output from one of the lost datanodes. The
> heartbeating thread seems to be locked up.
> This jira is to track a fix for the problem.
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