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https://issues.apache.org/jira/browse/CASSANDRA-1470?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12906316#action_12906316
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Jonathan Ellis commented on CASSANDRA-1470:
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The best option looks like using direct io to bypass the os cache during this
(and, similarly, for range scans) -- see
http://chbits.blogspot.com/2010/06/lucene-and-fadvisemadvise.html for why
posix_fadvise won't work. Looking at the source, posix_madvise doesn't look
good either (VM_SEQ_READ and VM_RAND_READ are ignored once set).
> use direct io for compaction
> ----------------------------
>
> Key: CASSANDRA-1470
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1470
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Fix For: 0.6.6
>
>
> When compaction scans through a group of sstables, it forces the data in the
> os buffer cache being used for hot reads, which can have a dramatic negative
> effect on performance.
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