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https://issues.apache.org/jira/browse/HBASE-4497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13116695#comment-13116695
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Jonathan Gray commented on HBASE-4497:
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startcode and timestamp is what i initially thought of. seems like there could
be some weird situations. for example, what is to say that the server already
in META didn't somehow become the new assignment destination?
or what if... M tells RS1 to OPEN R1 and to expect RS3:StartCode3 in META. RS1
locks up right before doing the META edit, M tells RS2 to OPEN R1 and to also
expect RS3:StartCode3 in META. I guess this is the atomicity we need, so that
should be okay.
one neat idea would be to introduce this region assignment incrementing ID into
META. it would provide a nice way to debug the movement of a region across the
cluster over time and could also provide the necessary info to use CheckAndPut.
> 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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