[Gluster-users] Performance

[Mohit Anchlia]

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
>> >
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