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From Peter Schuller <peter.schul...@infidyne.com>
Subject Re: Commitlog Disk Full
Date Thu, 12 May 2011 18:41:54 GMT
> I understand that cassandra periodically cleans up the commitlog directories
> by generating sstables in datadir. Is there any way to speed up this
> movement from commitog to datadir?

commitlog_rotation_threshold_in_mb could cause problems if it was set
very very high, but with the default of 128mb it should not be an
issue.

I suspect the most likely reason is that you have a column family
whose memtable flush settings are extreme. A commit log segment cannot
be removed until the corresponding data has been flushed to an
sstable. For high-throughput memtables where you flush regularly this
should happen often. For idle or almost idle memtables you may be
waiting on the timeout criteria to trigger. So in general, having a
memtable with a long expiry time will have the potential to generate
commit logs of whatever size is implied by the write traffic during
that periods.

The memtable setting in question is the "memtable_flush_after"
setting. Do you have that set to something very high on one of your
column families?

You can use "describe keyspace name_of_keyspace" in cassandra-cli to
check current settings.

-- 
/ Peter Schuller

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