Can you run that test with oflag=direct and see that is what you get? On Wed, Apr 20, 2011 at 2:43 PM, paul simpson <paul at realisestudio.com> wrote: > many thanks for sharing guys. ?an informative read indeed! > i've 4x dells - each running 12 drives on PERC 600. ?was dissapointed to > hear they're so bad! ?we never got round to doing intensive tests this in > depth. ?12x2T WD RE4 (sata) is giving me ~600Mb/s write on the bare > filesystem. ?joe, does that tally with your expectations for 12 SATA drives > running RAID6? ?(i'd put more faith in your gut reaction than our last > tests...) ?;) > -p > > On 20 April 2011 21:02, Mohit Anchlia <mohitanchlia at gmail.com> wrote: >> >> 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 >> > >> _______________________________________________ >> Gluster-users mailing list >> Gluster-users at gluster.org >> http://gluster.org/cgi-bin/mailman/listinfo/gluster-users > >
