Saturday, May 05, 2007

Edinburgh disk benchmarks

I ran some Edinburgh disk benchmarks over the past couple of days in order to obtain a comparison of the performance of the IBM disk to the university SAN. It's not an entirely fair comparison as the IBM disk uses fibre channel to talk to pool1 (beefy 16GB RAM server) while the SAN uses FC to talk to pool2 (2GB of RAM). Both systems as configured to use RAID5, but they use a different number of disk in each array. You can find the results here:

http://www.ph.ed.ac.uk/~gcowan1/edinburgh-disk-benchmark-07-05.ps

I used tiobench (threaded IO) to perform the testing. It is quite clear that there is a limit of ~100MB/s on sequential operations with the IBM disk, while for the SAN it appears to be ~50MB/s. I need to check if this is a limit with the FC connection, I had thought we should see better performance. As expected the rate for random IO increases as the block size increases. There does not appear to be any significant difference between the two sets of disks when looking at the random metrics.

I'll post some results from Glasgow soon.

2 comments:

Elwell said...

Grieg, we saw nmon on an IBM attached box to the SAN top out at ~ 40MB/s I/O rate - This was a large (16TB+) array using a single HBA (yes I know it's a stupid system design, but hey... it's um, the pretty colours lot :-)

Greig A Cowan said...

I should have added that both filesystems being tested were ext3 with noatime and nodiratime mount options. Both were formatted with the large_file feature, as reported by dumpe2fs.