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https://issues.apache.org/jira/browse/HBASE-27999?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17766837#comment-17766837
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Wellington Chevreuil commented on HBASE-27999:
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Thanks for this contribution [~ragarkar], I have merged the PR into the feature
branch for now. Could you fill up the release notes field explaining briefly
how this works and how this function can be enabled?
> Implement cache aware load balancer
> -----------------------------------
>
> Key: HBASE-27999
> URL: https://issues.apache.org/jira/browse/HBASE-27999
> Project: HBase
> Issue Type: Sub-task
> Components: Balancer
> Reporter: Rahul Agarkar
> Assignee: Rahul Agarkar
> Priority: Major
>
> HBase uses ephemeral cache to cache the blocks by reading them from the slow
> storages and storing them to the bucket cache. This cache is warmed up
> everytime a region server is started. Depending on the data size and the
> configured cache size, the cache warm up can take anywhere between a few
> minutes to few hours. Doing this everytime the region server starts can be a
> very expensive process. To eliminate this, HBASE-27313 implemented the cache
> persistence feature where the region servers periodically persist the blocks
> cached in the bucket cache. This persisted information is then used to
> resurrect the cache in the event of a region server restart because of normal
> restart or crash.
> This feature aims at enhancing this capability of HBase to enable the
> balancer implementation considers the cache allocation of each region on
> region servers when calculating a new assignment plan and uses the
> region/region server cache allocation info reported by region servers which
> takes into account to calculate the percentage of HFiles cached for each
> region on the hosting server, and then use that as another factor when
> deciding on an optimal, new assignment plan.
>
> A design document describing the balancer can be found at
> https://docs.google.com/document/d/1A8-eVeRhZjwL0hzFw9wmXl8cGP4BFomSlohX2QcaFg4/edit?usp=sharing
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