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https://issues.apache.org/jira/browse/HBASE-15249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15143049#comment-15143049
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Anoop Sam John commented on HBASE-15249:
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Normalizer just checks the region size and decide on merge? Ya when a region
is getting write requests (even if very less than 10%) we should not allow to
merge it IMHO.. This means the region is growing. When 2 regions stop
getting any write reqs and may be only have read request/or even that also not,
it can be considered for merge.
> 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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