[jira] [Commented] (HBASE-15128) Disable region splits and merges switch in master

["Enis Soztutar (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-15128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15149384#comment-15149384 ] 

Enis Soztutar commented on HBASE-15128:
---------------------------------------

Some discussion at http://search-hadoop.com/m/YGbbNWhXFZ3NtM/Dynamic+switches+in+master&subj=+DISCUSS+Dynamic+switches+in+master but not much conclusion. We should still go ahead with this patch somehow. Should we change set_switch to set_merge_switch and set_split_switch and get this in? We need this for supporting big clusters where region splits happen every couple of minutes. 

> Disable region splits and merges switch in master
> -------------------------------------------------
>
>                 Key: HBASE-15128
>                 URL: https://issues.apache.org/jira/browse/HBASE-15128
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Enis Soztutar
>            Assignee: Heng Chen
>             Fix For: 2.0.0, 1.3.0
>
>         Attachments: HBASE-15128.patch, HBASE-15128_v1.patch, HBASE-15128_v3.patch
>
>
> In large clusters where region splits are frequent, and HBCK runs take longer, the concurrent splits cause further problems in HBCK since HBCK assumes a static state for the region partition map. We have just seen a case where HBCK undo's a concurrently splitting region causing number of inconsistencies to go up. 
> We can have a mode in master where splits and merges are disabled like the balancer and catalog janitor switches. Master will reject the split requests if regionservers decide to split. This switch can be turned on / off by the admins and also automatically by HBCK while it is running (similar to balancer switch being disabled by HBCK). 
> HBCK  should also disable the Catalog Janitor just in case. 



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