On Mon, 10 Jan 2011, Joe Landman wrote: > 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. What hardware gives you 2+GB/s? I am using the 16 port 3Ware 9750 cards with fast drives and I dont get close to that. -Nathan
