Hi We use amazon ami 3.2.12-3.2.4.amzn1.x86_64
and some of our data file are more than 10G thanks koji 2012-5-16 下午6:00 於 "aaron morton" <aa...@thelastpickle.com> 寫道： > 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 > > >
