On Ubuntu ? Sounds like http://wiki.apache.org/cassandra/FAQ#ubuntu_hangs
Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 16/05/2012, at 2:13 PM, koji Lin wrote: > Hi > > Our service already run cassandra 1.0 on 1x ec2 instances(with ebs), and we > saw lots of discussion talk about using ephemeral raid for better > performance and consistent performance. > > So we want to create new instance using 4 ephemeral raid0, and copy the data > from ebs to finally replace the old instance and reduce some . > > we create the xlarge instance with -b '/dev/sdb=ephemeral0' -b > '/dev/sdc=ephemeral1' -b '/dev/sdd=ephemeral2' -b '/dev/sde=ephemeral3', > > and use mdadm command like this mdadm --create /dev/md0 --level=0 -c256 > --raid-devices=4 /dev/sdb /dev/sdc /dev/sdd /dev/sde > > after copying file and start the cassandra(same token as old instance it > replaced). > > we saw the read is really fast always keep 2xxm/sec, but system load exceed > 40, with high iowait, and lots of client get timeout result. We guess maybe > it's the problem of ec2 instance, so we create another one with same setting > to replace other machine ,but the result is same . Then we rollback to ebs > with single disk ,read speed keeps at 1xmb/sec but system becomes well > .(using ebs with 2 disks raid0 will keep at 2xmb/sec and higher iowait then > single disk ,but still works) > > Is there anyone meet the same problem too ? or do we forget something to > configure? > > thank you > > koji >
