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From Olivier Mallassi <omalla...@octo.com>
Subject Re: ec2 tests
Date Sat, 19 Jun 2010 00:39:15 GMT
I tried the following :
- always one cassandra node on one EC2 m.large instance. two other m.large
instance, I run 4 stress.py (50 thread each, 2 stress.py on each instance)
- RAID0 EBS for data and ephemeral EBS (/dev/sda1 partition) for commit log.
- -Xmx4G

and I did not see any improvements (Cassandra stays around 7000 W/sec).

CPU is running up to 130% (spike) but I have two 2,5Ghz CPU
the avgqu-sz goes up to 20 (sometimes more) (for the device /dev/sda1 that
stores the commitlog)

Do you think concurrentWrites or MemtableThroughputInMB parameters must be
increased (using default value right now)
Any suggestions are welcomed. ;o)

On Fri, Jun 18, 2010 at 7:42 PM, Benjamin Black <b@b3k.us> wrote:

> On Fri, Jun 18, 2010 at 8:00 AM, Olivier Mallassi <omallassi@octo.com>
> wrote:
> > I use the default conf settings (Xmx 1G, concurrentwrite 32...) except
> for
> > commitlog and DataFileDirectory : I have a raid0 EBS for commit log and
> > another raid0 EBS for data.
> > I can't get through 7500 write/sec (when launching 4 stress.py in the
> same
> > time).
> > Moreover I can see some pending tasks in the
> > org.cassandra.db.ColumnFamilyStores.Keyspace1.Standard1 MBean
> > Any ideas on the bottleneck?
>
> Your instance has 7.5G of RAM, but you are limiting Cassandra to 1G.
> Increase -Xmx to 4G for a start.  You are likely to get significantly
> better performance with the ephemeral drive, as well.  I suggest
> testing with commitlog on the ephemeral drive for comparison.
>
>
> b
>



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Olivier Mallassi
OCTO Technology
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