Thanks a lot for taking time and effort. I will try raw performance first but that will only be going to one disk instead of 4. But I think it definitely makes sense as the first step. On Wed, Apr 20, 2011 at 12:53 PM, Joe Landman <landman at scalableinformatics.com> wrote: > On 04/20/2011 03:43 PM, Mohit Anchlia wrote: >> >> Thanks! Is there any recommended configuration you want me to use when >> using mdadm? >> >> I got this link: >> >> http://tldp.org/HOWTO/Software-RAID-HOWTO-5.html#ss5.1 > > First things first, break the RAID0, and then lets measure performance per > disk, to make sure nothing else bad is going on. > > ? ? ? ?dd if=/dev/zero of=/dev/DISK bs=128k count=80k oflag=direct > ? ? ? ?dd of=/dev/null if=/dev/DISK bs=128k count=80k iflag=direct > > for /dev/DISK being one of the drives in your existing RAID0. ?Once we know > the raw performance, I'd suggest something like this > > ? ? ? ?mdadm --create /dev/md0 --metadata=1.2 --chunk=512 \ > ? ? ? ? ? ? ? ?--raid-devices=4 /dev/DISK1 /dev/DISK2 ? ? \ > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? /dev/DISK3 /dev/DISK4 > ? ? ? ?mdadm --examine --scan | grep "md\/0" >> /etc/mdadm.conf > > then > > ? ? ? ?dd if=/dev/zero of=/dev/md0 bs=128k count=80k oflag=direct > ? ? ? ?dd of=/dev/null if=/dev/md0 bs=128k count=80k iflag=direct > > and lets see how it behaves. ?If these are good, then > > ? ? ? ?mkfs.xfs -l version=2 -d su=512k,sw=4,agcount=32 /dev/md0 > > (yeah, I know, gluster folk have a preference for ext* ... we generally > don't recommend ext* for anything other than OS drives ... you might need to > install xfsprogs and the xfs kernel module ... which kernel are you using > BTW?) > > then > > ? ? ? ?mount -o logbufs=4,logbsize=64k /dev/md0 /data > ? ? ? ?mkdir stress > > > ? ? ? ?dd if=/dev/zero of=/data/big.file bs=128k count=80k oflag=direct > ? ? ? ?dd of=/dev/null if=/data/big.file bs=128k count=80k iflag=direct > > and see how it handles things. > > When btrfs finally stabilizes enough to be used, it should be a reasonable > replacement for xfs, but this is likely to be a few years. > > -- > Joseph Landman, Ph.D > Founder and CEO > Scalable Informatics Inc. > email: landman at scalableinformatics.com > web ?: http://scalableinformatics.com > ? ? ? http://scalableinformatics.com/sicluster > phone: +1 734 786 8423 x121 > fax ?: +1 866 888 3112 > cell : +1 734 612 4615 >
