On Fri, Jun 18, 2010 at 05:15:44AM -0400, Thomas Burgess wrote: > On Fri, Jun 18, 2010 at 4:42 AM, Pasi Kärkkäinen <[1]pa...@iki.fi> wrote: > > On Fri, Jun 18, 2010 at 01:26:11AM -0700, artiepen wrote: > > Well, I've searched my brains out and I can't seem to find a reason > for this. > > > > I'm getting bad to medium performance with my new test storage device. > I've got 24 1.5T disks with 2 SSDs configured as a zil log device. I'm > using the Areca raid controller, the driver being arcmsr. Quad core AMD > with 16 gig of RAM OpenSolaris upgraded to snv_134. > > > > The zpool has 2 11-disk raidz2's and I'm getting anywhere between > 1MB/sec to 40MB/sec with zpool iostat. On average, though it's more like > 5MB/sec if I watch while I'm actively doing some r/w. I know that I > should be getting better performance. > > > > How are you measuring the performance? > Do you understand raidz2 with that big amount of disks in it will give > you really poor random write performance? > -- Pasi > > i have a media server with 2 raidz2 vdevs 10 drives wide myself without a > ZIL (but with a 64 gb l2arc) > I can write to it about 400 MB/s over the network, and scrubs show 600 > MB/s but it really depends on the type of i/o you have....random i/o > across 2 vdevs will be REALLY slow (as slow as the slowest 2 drives in > your pool basically) > 40 MB/s might be right if it's random....though i'd still expect to see > more. >
7200 RPM SATA disk can do around 120 IOPS max (7200/60 = 120), so if you're doing 4 kB random IO you end up getting 4*120 = 480 kB/sec throughput max from a single disk (in the worst case). 40 MB/sec of random IO throughput using 4 kB IOs would be around 10240 IOPS.. you'd need 85x SATA 7200 RPM disks in raid-0 (striping) for that :) -- Pasi _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
