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https://issues.apache.org/jira/browse/CASSANDRA-12228?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15404078#comment-15404078
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Marcus Eriksson commented on CASSANDRA-12228:
---------------------------------------------
Since 6696 the configuration sets how many flush writers there should be *per
data directory* - so factoring in the number of data directories in the
calculation is probably wrong (ie, with 10 data directories and 2 memtable
flush writers you would get 20 threads actually doing writing to disk and 2
threads waiting on the writing, meaning we can flush 2 memtables concurrently)
> Write performance regression in 3.x vs 3.0
> ------------------------------------------
>
> Key: CASSANDRA-12228
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12228
> Project: Cassandra
> Issue Type: Bug
> Reporter: T Jake Luciani
> Assignee: Ariel Weisberg
> Priority: Minor
> Fix For: 3.9
>
>
> I've been tracking down a performance issue in trunk vs cassandra-3.0 branch.
> I think I've found it. CASSANDRA-6696 changed the default memtable flush
> default to 1 vs the min of 2 in cassandra-3.0.
> I don't see any technical reason for this and we should add back the min of 2
> sstable flushers per disk.
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