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From John Watson <j...@disqus.com>
Subject hot sstables evicted from page cache on compaction causing high latency
Date Fri, 12 Jul 2013 21:15:45 GMT
Having a real issue where at the completion of large compactions, it will
evict hot sstables from the kernel page cache causing huge read latency
while it is backfilled.

https://dl.dropboxusercontent.com/s/149h7ssru0dapkg/Screen%20Shot%202013-07-12%20at%201.46.19%20PM.png

Blue line - page cache
Green line - disk read latency (ms)
Red line - CF read latency (ms)

The beginning of both high latency plateaus correspond with the completion
of a compaction.

Seems like applying/enabling this will help?
https://issues.apache.org/jira/browse/CASSANDRA-4937

- C* 1.2.6
- 3 Nodes
- 24G RAM (8G heap)
- (2) 3TB 7.2k disks using JBOD feature of C*

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