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https://issues.apache.org/jira/browse/HBASE-920?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack updated HBASE-920:
------------------------
Attachment: hbase-920.patch
Adds a slop configuration. Now we balance only if a regionserver has (average
+ (average * slop)) regions. Default is 10%. Patch includes reordering of
hbase-default.xml grouping master and regionserver configuration.
> Make region balancing sloppier
> ------------------------------
>
> Key: HBASE-920
> URL: https://issues.apache.org/jira/browse/HBASE-920
> Project: Hadoop HBase
> Issue Type: Improvement
> Reporter: stack
> Assignee: stack
> Fix For: 0.18.1
>
> Attachments: hbase-920.patch
>
>
> The region load balancer is exacting. Here's the logic:
> {code}
> if (avgLoad > 2.0 && thisServersLoad.getNumberOfRegions() > avgLoad) {
> if (LOG.isDebugEnabled()) {
> LOG.debug("Server " + serverName + " is overloaded. Server load:
> " +
> thisServersLoad.getNumberOfRegions() + " avg: " + avgLoad);
> }
> ...
> {code}
> On a cluster of thousands of regions, especially around startup or if there's
> been a crash, the above makes for a bunch of churn as load balancer closes
> and opens nodes to achieve an exact balance (all nodes must be <= to average).
> I'd suggest that nodes should be left alone if they are within some
> percentage of the average -- say 10% (should be configurable).
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