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From aaron morton <aa...@thelastpickle.com>
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
https://github.com/apache/cassandra/blob/cassandra-0.8.0/NEWS.txt#L34
http://thelastpickle.com/2011/05/04/How-are-Memtables-measured/

Cheers


-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

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: scode@scode.org [mailto:scode@scode.org] On Behalf Of Peter Schuller
> Sent: Tuesday, June 21, 2011 9:13 AM
> To: user@cassandra.apache.org
> 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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