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https://issues.apache.org/jira/browse/HBASE-18002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16000320#comment-16000320
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Anoop Sam John commented on HBASE-18002:
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I mean this. From SSD, the reads/writes happen as pages and update as blocks.
See here
http://codecapsule.com/2014/02/12/coding-for-ssds-part-6-a-summary-what-every-programmer-should-know-about-solid-state-drives/.
When the file is already having data, we will overhead of writing new cache
entries. When our blocks are not aligned with pages in SSD (mostly yes this
way), we will end up have to rewrite more pages/blocks to add an HFile block
entry!
bq.bigger concern is that if there are lot of evictions and new blocks keeps
getting filled up we may still end up with the same problem right?
Hmm true.. Need tests!
> Investigate why bucket cache filling up in file mode in an exisitng file is
> slower
> -----------------------------------------------------------------------------------
>
> Key: HBASE-18002
> URL: https://issues.apache.org/jira/browse/HBASE-18002
> Project: HBase
> Issue Type: Sub-task
> Components: BucketCache
> Affects Versions: 2.0.0
> Reporter: ramkrishna.s.vasudevan
> Fix For: 2.0.0
>
>
> This issue was observed when we recently did some tests with SSD based bucket
> cache. Similar thing was also reported by @stack and [~danielpol] while doing
> some of these bucket cache related testing.
> When we try to preload a bucket cache (in file mode) with a new file the
> bucket cache fills up quite faster and there not much 'failedBlockAdditions'.
> But when the same bucket cache is filled up with a preexisitng file ( that
> had already some entries filled up) this time it has more
> 'failedBlockAdditions' and the cache does not fill up faster. Investigate why
> this happens.
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