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Posted to issues@hbase.apache.org by "ramkrishna.s.vasudevan (Commented) (JIRA)" <ji...@apache.org> on 2012/02/02 19:00:54 UTC
[jira] [Commented] (HBASE-4177) Handling read failures during recovery - when HMaster calls Namenode recovery, recovery may be a failure leading to read failure while splitting logs
[ https://issues.apache.org/jira/browse/HBASE-4177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13199033#comment-13199033 ]
ramkrishna.s.vasudevan commented on HBASE-4177:
-----------------------------------------------
Any suggestions on this. We tend to run into this problem every now and then.
> 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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