[jira] [Issue Comment Edited] (HBASE-5875) Process RIT and Master restart may remove an online server considering it as a dead server

["ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-5875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13267392#comment-13267392 ] 

ramkrishna.s.vasudevan edited comment on HBASE-5875 at 5/3/12 12:44 PM:
------------------------------------------------------------------------

bq.What is the above referring to? Which part of the code?

In assignRootAndMeta()
{code}
boolean rit = this.assignmentManager.
      processRegionInTransitionAndBlockUntilAssigned(HRegionInfo.ROOT_REGIONINFO);

{code}
bq.Can the master not detect this corner case just by looking at whats in zk?
Here zk you mean the RS node or the ROOT region node?
                
      was (Author: ram_krish):
    bq.What is the above referring to? Which part of the code?

In assignRootAndMeta()
{code}
boolean rit = this.assignmentManager.
      processRegionInTransitionAndBlockUntilAssigned(HRegionInfo.ROOT_REGIONINFO);

{code}

                  
> 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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