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https://issues.apache.org/jira/browse/HBASE-2821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14096416#comment-14096416
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Nick Dimiduk commented on HBASE-2821:
-------------------------------------
This is an interesting idea. It probably looks a bit different in a world with
HDFS storage tiers. In the mean time, this patch is reasonable to emulate the
Colossus style (non-chained) writes.
bq. So eliminating the third replica without changing block placement policy
doesn't buy us much (if anything)
Even if going off-rack, it probably buys us a good bit on the long tail. I'd
like to try it out and see what we see.
cc [~nkeywal].
> Keep young storefiles at lower replication
> ------------------------------------------
>
> Key: HBASE-2821
> URL: https://issues.apache.org/jira/browse/HBASE-2821
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Todd Lipcon
> Assignee: Andrew Purtell
> Fix For: 2.0.0
>
> Attachments: HBASE-2821.patch, lifetime-distribution.png,
> storefile_age.pl
>
>
> jgray and I were brainstorming some ideas about this:
> In a typical heavy-write scenario, many store files do not last very long.
> They're flushed and then within a small number of seconds a compaction runs
> and they get deleted. For these "short lifetime" store files, it's less
> likely that a failure will occur during the window in which they're valid.
> So, I think we can consider some optimizations like the following:
> - Flush files at replication count 2. Scan once a minute for any store files
> in the region that are older than 2 minutes. If they're found, increase their
> replication to 3. (alternatively, queue them to avoid scanning)
> - More dangerous: flush files at replication count 1, but don't count them
> when figuring log expiration. So, if they get lost, we force log splitting to
> recover.
> The performance gain here is that we avoid the network and disk transfer of
> writing the third replica for a file that we're just about to delete anyway.
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