I believe Zpool iostat will include cached IO's, and write IO's which will be coalesced into a single physical IO to your disk.
The plain "iostat" command is a good place to start to see what's actually going to disk. "iostat -dxzcn 1" is what comes out my fingers automatically, although I vary the interval, and often add "CM" the options. My number of "100" IOP/s per disk is a general number on what a SATA drive can do, it's very much a rough guide. It's usually quite easy to show in benchmarks that a given sata drive will do 150-200 or sometimes even more, although generally such benchmarks only us a relatively small portion of the disk, and so hide disk seek latencies. On a shared use system, where the drive is likely to be 40-80% full, with "hot" data spread all across the drive, those seek times really start to come back into it. In terms of IOP/s, disks really haven't gotten much faster at all over the last 10 years. Bring on the flash revolution! :-) T. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Roman Naumenko Sent: Friday, 21 August 2009 12:08 AM To: [email protected] Subject: Re: [storage-discuss] Restricting initiator resource consumption > If your pool has few vdevs (I believe you had a single raid-z), then this will be slow, as you will probably get only about 100 IOP/s from your pool. My exchange server happily produces 1500 IOP/s in daily use, and would go higher but our current array wont go any faster for un-cached IO. :-)<p> How do you check iops?</br> I saw "writes" > 1000 in zpool iostat when I tested pool with sqlio over iscsi.</br> But it was async, of course.</br> I didn't find a way to make sync synthetic writes on windows, so I'm waiting fr exchange to see what kind of writes it makes.</br> <p> >>> Even with a dedicated SAN and 15K/rpm drives, MS generally recommend >>> Raid-10 configurations for exchange. Raid-5/6, or RaidZ1/2 usually >>> doesn't give the IOP/s rates you need - although many people do anyway.<br> <p> >> That's why I'd like to use SSD - to improve iops to a desirable level. <p> > Only if you get a reasonable cache hit rate. I suspect that a combination of exchange and sql server is likely to result in a fairly poor hit rate - certainly not enough to alleviate the performance bottleneck of a single vdev. <p> I meant slog - to improve iops for wites. Reading cache is not a big deal right now. --<p> Roman Naumenko</br> [email protected] Message was edited by: rokka -- This message posted from opensolaris.org _______________________________________________ storage-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/storage-discuss ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ _______________________________________________ storage-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/storage-discuss
