[jira] [Commented] (HBASE-21035) Meta Table should be able to online even if all procedures are lost

["Michael Stack (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-21035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16979442#comment-16979442 ] 

Michael Stack commented on HBASE-21035:
---------------------------------------

To address more directly [~allan163]'s original description:

 "Since no one will bring meta region online."

We added 'fix' to hbck2 to address above.

'hbck2 --skip assigns 1588230740' will force assign of hbase:meta if Master stuck in startup waiting on hbase:meta to online AND no Procedure to assign hbase:meta (because for example, MasterProcWALs have all been removed.... or are corrupt). See the help usage from hbck2 for the assigns command. Will also work for namespace region assign (HBASE-21156).



{quote} assigns [OPTIONS] <ENCODED_REGIONNAME>...
   Options:
    -o,--override  override ownership by another procedure
   A 'raw' assign that can be used even during Master initialization (if
   the -skip flag is specified). Skirts Coprocessors. Pass one or more
   encoded region names. 1588230740 is the hard-coded name for the
   hbase:meta region and de00010733901a05f5a2a3a382e27dd4 is an example of
   what a user-space encoded region name looks like. For example:
     $ HBCK2 assign 1588230740 de00010733901a05f5a2a3a382e27dd4
   Returns the pid(s) of the created AssignProcedure(s) or -1 if none.{quote}

> Meta Table should be able to online even if all procedures are lost
> -------------------------------------------------------------------
>
>                 Key: HBASE-21035
>                 URL: https://issues.apache.org/jira/browse/HBASE-21035
>             Project: HBase
>          Issue Type: Sub-task
>    Affects Versions: 2.1.0
>            Reporter: Allan Yang
>            Assignee: Allan Yang
>            Priority: Major
>         Attachments: HBASE-21035.branch-2.0.001.patch, HBASE-21035.branch-2.1.001.patch
>
>
> After HBASE-20708, we changed the way we init after master starts. It will only check WAL dirs and compare to Zookeeper RS nodes to decide which server need to expire. For servers which's dir is ending with 'SPLITTING', we assure that there will be a SCP for it.
> But, if the server with the meta region crashed before master restarts, and if all the procedure wals are lost (due to bug, or deleted manually, whatever), the new restarted master will be stuck when initing. Since no one will bring meta region online.
> Although it is an anomaly case, but I think no matter what happens, we need to online meta region. Otherwise, we are sitting ducks, noting can be done.



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