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. Chris ----- "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 > be > > able to get a lot more speed than I am with some pretty basic > tests. > > Maybe someone running Infiniband can confirm that what I am seeing > is > > 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 > system. > > 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 > you > traverse takes performance away (you lose it in stack inefficiency). > So > 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 > 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
