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https://issues.apache.org/jira/browse/HBASE-13170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14351470#comment-14351470
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Elliott Clark commented on HBASE-13170:
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Yes SSD's allow you to persist block cache between restarts. However that's not
actually that helpful for some of my services.
The current bucket cache does not allow two or more regionservers to share the
same cache.Moving single regions for rolling restart can roll them to a full
block cache. I can re-deploy at any time and the rolling restart only adds the
latency of close/open region. It doesn't add the latency of a cold block cache.
Read replicas can warm and share each other's cache. No need for double the
memory just because there is a read replica.
Additionally memcached is faster than the cheap ssd's and memory will last for
many many more write cycles. No need to worry about wear leveling, or SSD
garbage collection, erasure pages, etc.
Finally memcache allows scaling the read caching of a HBase cluster independent
of expensive storage nodes.
> Allow block cache to be external
> --------------------------------
>
> Key: HBASE-13170
> URL: https://issues.apache.org/jira/browse/HBASE-13170
> Project: HBase
> Issue Type: New Feature
> Components: io
> Affects Versions: 2.0.0
> Reporter: Elliott Clark
> Assignee: Elliott Clark
> Fix For: 1.1.0
>
>
> Allow an external service to provide the block cache. This has the nice
> property of allowing failover/upgrades to happen without causing a fully cold
> cache.
> Additionally this allows read replicas to share some of the same memory.
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