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https://issues.apache.org/jira/browse/HBASE-5875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13266429#comment-13266429
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ramkrishna.s.vasudevan commented on HBASE-5875:
-----------------------------------------------

@Chunhui
Correct but that is still the RIT map is cleared. But the actual assignment is 
done after the region is added to the online map in the RS side and that is 
where this problem happened.
You know that in verifyRootRegionLocation() we mainly check if the region is 
available on the region server online list.
So there is still a small time gap for this to happen and this happened in our 
test cluster. :)
Thanks for your time.
                
> 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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