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Date: Wed, 28 Sep 2011 04:33:45 +0000 (UTC)
From: "dhruba borthakur (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-4497) If region opening fails after
 updating META HBCK reports it as inconsistent and scanning the region
 throws NSRE
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    [ https://issues.apache.org/jira/browse/HBASE-4497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13116139#comment-13116139 ] 

dhruba borthakur commented on HBASE-4497:
-----------------------------------------

Can somebody pl elaborate any disadvantages if we make the master be the only entity that can update META about where the region is being served from?
                
> If region opening fails after updating META HBCK reports it as inconsistent and scanning the region throws NSRE
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-4497
>                 URL: https://issues.apache.org/jira/browse/HBASE-4497
>             Project: HBase
>          Issue Type: Bug
>            Reporter: ramkrishna.s.vasudevan
>            Priority: Critical
>
> As per the discussion in the mail chain "HBCK reporting of possible mismatch in RS assignment" this JIRA is created.
> Consider two RS-> RS1 and RS2.
> A region tries to open in RS1. But it takes a while.  The RS1 has still not updated meta and transitioned the node from OPENING to OPENED
> So timeout assigns the region to RS2.  RS2 successfully updates the META and opens the region.
> Now RS1 tries to act on the region by first updating the META and then transiting the node to OPENING to OPENED.
> RS1 transiting the node to OPENING to OPENED will fail.  But the META entry will have RS1 as the latest.
> Now HBCK reports this as an inconsistency and if we try to scan the Region we get NotServingRegionException.

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