[Gluster-users] infiniband speed
chawkins at bplinux.com
Tue Jan 11 06:01:57 UTC 2011
Thanks Joe, you nailed it. These are just test machines and in each case, just a single 10k scsi drive. That is the throughput bottleneck... I was not able to get more than 70MB/s sustained.
----- "Joe Landman" <landman at scalableinformatics.com> wrote:
> On 01/10/2011 07:43 PM, Christopher Hawkins wrote:
> > I am testing Infiniband for the first time. It seems that I should
> > able to get a lot more speed than I am with some pretty basic
> > Maybe someone running Infiniband can confirm that what I am seeing
> > way out of line, and/or help diagnose?
> What is the underlying disk speed?
> Try this:
> # (on bravo)
> dd if=/dev/zero of=/cluster/shadow/big.file bs=1M count=20k
> This will write a 20GB file to the same partition. We need to see how
> fast that write is (outside of cache)
> Do the same test on the other machine.
> Infiniband won't make slow disks fast. So unless you are already
> getting a gigabyte or two per second (we do on our units), adding
> Infiniband won't get you any significant additional performance.
> Put another way, you are bound by the slowest aspect of your storage
> What are your underlying disks? Are these individual drives? RAID?
> What sort of RAID if it is a RAID? How is it organized?
> We tune our systems pretty hard, so we start with 2+GB/s for TB sized
> files before we ever touch the next stack up. Each additional stack
> traverse takes performance away (you lose it in stack inefficiency).
> you should start out with as fast a system as you possibly can, so you
> don't lose too much performance.
> Joseph Landman, Ph.D
> Founder and CEO
> Scalable Informatics, Inc.
> email: landman at scalableinformatics.com
> web : http://scalableinformatics.com
> phone: +1 734 786 8423 x121
> fax : +1 866 888 3112
> cell : +1 734 612 4615
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