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https://issues.apache.org/jira/browse/HBASE-4177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13440652#comment-13440652
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nkeywal commented on HBASE-4177:
--------------------------------
hum, it's really closed to what I've done, but this problem may still be there.
Ram, what do you think? If you don't have the time, I can give it a try.
> Handling read failures during recovery - when HMaster calls Namenode
> recovery, recovery may be a failure leading to read failure while splitting
> logs
> ------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-4177
> URL: https://issues.apache.org/jira/browse/HBASE-4177
> Project: HBase
> Issue Type: Bug
> Components: master
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Priority: Critical
>
> As per the mailing thread with the heading
> 'Handling read failures during recovery' we found this problem.
> As part of split Logs the HMaster calls Namenode recovery. The recovery is
> an asynchronous process.
> In HDFS
> =======
> Even though client is getting the updated block info from Namenode on first
> read failure, client is discarding the new info and using the old info only
> to retrieve the data from datanode. So, all the read
> retries are failing. [Method parameter reassignment - Not reflected in
> caller].
> In HBASE
> =======
> In HMaster code we tend to wait for 1sec. But if the recovery had some
> failure then split log may not happen and may lead to dataloss.
> So may be we need to decide upon the actual delay that needs to be introduced
> once Hmaster calls NN recovery.
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