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https://issues.apache.org/jira/browse/HBASE-4177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13440919#comment-13440919
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ramkrishna.s.vasudevan commented on HBASE-4177:
-----------------------------------------------
@N
I too think the problem is still there. But internally here also we have not
started working on this yet. At that time we had discussions that HDFS side
also we need some changes and Stack has already raised the same in HDFS JIRA.
Surely you can take a stab at it N.
> 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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