[jira] [Commented] (HBASE-15249) Provide lower bound on number of regions in region normalizer for pre-split tables

["Ted Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-15249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15141875#comment-15141875 ] 

Ted Yu commented on HBASE-15249:
--------------------------------

Alternatively, we can retrieve write request counts from RegionLoad for the regions.
If the two regions to be merged happen to receive the most write requests, don't merge them in the current iteration.

> Provide lower bound on number of regions in region normalizer for pre-split tables
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-15249
>                 URL: https://issues.apache.org/jira/browse/HBASE-15249
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Assignee: Ted Yu
>         Attachments: HBASE-15249.v1.txt, HBASE-15249.v2.txt
>
>
> AMS (Ambari Metrics System) developer found the following scenario:
> Metrics table was pre-split with many regions on large cluster (1600 nodes).
> After some time, AMS stopped working because region normalizer merged the regions into few big regions which were not able to serve high read / write load.
> This is a big problem since the write requests flood the regions faster than the splits can happen resulting in poor performance.
> We should consider setting reasonable lower bound on region count.
> If the table is pre-split, we can use initial region count as the lower bound.



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