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From Sheng Chen <chensheng2...@gmail.com>
Subject Endless minor compactions after heavy inserts
Date Fri, 01 Apr 2011 03:52:12 GMT
I've got a single node of cassandra 0.7.4, and I used the java stress tool
to insert about 100 million records.
The inserts took about 6 hours (45k inserts/sec) but the following minor
compactions last for 2 days and the pending compaction jobs are still
increasing.

>From jconsole I can read the MemtableThroughputInMB=1499,
MemtableOperationsInMillions=7.0
But in my data directory, I got hundreds of 438MB data files, which should
be the cause of the minor compactions.

I tried to set compaction threshold by nodetool, but it didn't seem to take
effects (no change in pending compaction tasks).
After restarting the node, my setting is lost.

I want to distribute the read load in my disks (10 disks in xfs, LVM), so I
don't want to do a major compaction.
So, what can I do to keep the sstable file in a reasonable size, or to make
the minor compactions faster?

Thank you in advance.
Sheng

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