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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5875) Process RIT and Master restart may remove an online server considering it as a dead server
Date Wed, 02 May 2012 13:10:52 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13266539#comment-13266539
] 

ramkrishna.s.vasudevan commented on HBASE-5875:
-----------------------------------------------

@Chunhui
Yes, i took a look at HBASE-5819.
HBASE-5816 is also due to the serverShutdownHandlerEnabled variable. I think 'serverShutdownHandlerEnabled'
usage should be more clear.

I think that the problem of HBASE-4880 is applicable for the user regions but for root and
META the updates are done by the region servers themselves and the problem of HBASE-4880 should
not be there. Because if after updating the META entry to ROOT if transitioning to OPENED
fails, and even if closing the region also fails, any way till the META is available the system
is not going to function. Correct me if am wrong Chunhui.

                
> Process RIT and Master restart may remove an online server considering it as a dead server
> ------------------------------------------------------------------------------------------
>
>                 Key: HBASE-5875
>                 URL: https://issues.apache.org/jira/browse/HBASE-5875
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.92.1
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>             Fix For: 0.94.1
>
>         Attachments: HBASE-5875.patch
>
>
> If on master restart it finds the ROOT/META to be in RIT state, master tries to assign
the ROOT region through ProcessRIT.
> Master will trigger the assignment and next will try to verify the Root Region Location.
> Root region location verification is done seeing if the RS has the region in its online
list.
> If the master triggered assignment has not yet been completed in RS then the verify root
region location will fail.
> Because it failed 
> {code}
> splitLogAndExpireIfOnline(currentRootServer);
> {code}
> we do split log and also remove the server from online server list. Ideally here there
is nothing to do in splitlog as no region server was restarted.
> So master, though the server is online, master just invalidates the region server.
> In a special case, if i have only one RS then my cluster will become non operative.

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