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From aaron morton <>
Subject Re: CommitLog replay
Date Tue, 21 Jun 2011 19:13:40 GMT
use nodetool cfstats or show keyspaces; in cassandra-cli to see the flush settings, default
is (i think) 60 minutes, 0.1 million "ops" or 1/16th of hte heap size when the CF was created.

But under 0.8 there is an automagical global memory manager, see


Aaron Morton
Freelance Cassandra Developer

On 22 Jun 2011, at 01:51, Stephen Pope wrote:

> I've only got one cf, and haven't changed the default flush expiry period. I'm not sure
the node had fully started or not. I had to restart my data insertion (for other reasons),
so I can check the system log upon restart when the data is finished inserting.
> Do you know off-hand how long the default flush expiry period is?
> Cheers,
> Steve
> -----Original Message-----
> From: [] On Behalf Of Peter Schuller
> Sent: Tuesday, June 21, 2011 9:13 AM
> To:
> Subject: Re: CommitLog replay
>> I’ve got a single node deployment of 0.8 set up on my windows box. When I
>> insert a bunch of data into it, the commitlogs directory doesn’t clear upon
>> completion (should it?).
> It is expected that commit logs are retained for a while, and that
> there is reply going on when restarting a node. The main way to ensure
> that a smaller amount of commit log is active at any given moment, is
> to ensure that all column familes are flushed sufficiently often. This
> is because when column families are flushed, they are no longer
> necessitating the retention of the commit logs that contain the writes
> that were just flushed.
> Pay attention to whether you maybe have some cf:s that are written
> very rarely and won't flush until the flush expiry period.
>> As a result, when I stop and restart Cassandra it
>> replays all the commitlogs, then starts compacting (which seems like it’s
>> taking a long time). While it’s compacting it won’t talk to my test client.
> That it starts compacting is expected if the data flushed as a result
> of the commit log reply triggers compactions. However, compaction does
> not imply that the node refuses to talk to clients.
> Are you sure the node has fully started? it should log when it starts
> up the thrift interface - check system.log.
> -- 
> / Peter Schuller

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