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From Alexandru Dan Sicoe <sicoe.alexan...@googlemail.com>
Subject Re: commit log size
Date Tue, 29 Nov 2011 09:54:04 GMT
Ok, thanks!

On Mon, Nov 28, 2011 at 8:53 PM, Jeremiah Jordan <
jeremiah.jordan@morningstar.com> wrote:

> Yes, the low volume memtables are causing the problem.  Lower the
> thresholds for those tables if you don't want the commit logs to go crazy.
>
> -Jeremiah
>
>
> On 11/28/2011 11:11 AM, Alexandru Dan Sicoe wrote:
>
>> Hello everyone,
>>
>> 4 node Cassandra 0.8.5 cluster with RF=2, replica placement strategy =
>> SimpleStartegy, write consistency level = ANY, memtable_flush_after_mins
>> =1440; memtable_operations_in_**millions=0.1; memtable_throughput_in_mb
>> = 40; max_compaction_threshold =32; min_compaction_threshold =4;
>>
>> I have one keyspace with 1 CF for all the data and 3 other small CFs for
>> metadata. I am using Datastax OpsCenter to monitor my cluster so there is
>> another keyspace for monitoring.
>>
>> Everything works ok, the only thing I've noticed is this morning the
>> commitlog of one node was 52GB, one was 25 GB and the others were around 3
>> GB. I left everything untouched and looked a couple of hours later and the
>> 52GB one is now about 3GB and the 25 GB one is now 29 GB and the other two
>> about the same as before.
>>
>> Are my commit logs growing because of small memtables which don't get
>> flushed because they don't reach the operations and throughput limits? Then
>> why do only some nodes exhibit this behaviour?
>>
>> It would be interesting to understand how to control the size of the
>> commitlog also to know how to size my commitlog disks!
>>
>> Thanks,
>> Alex
>>
>


-- 
Alexandru Dan Sicoe
MEng, CERN Marie Curie ACEOLE Fellow

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