On Wed, 2011-06-01 at 12:54 -0400, Paul Kraus wrote: > I figure this group will know better than any other I have contact > with, is 700-800 I/Ops reasonable for a 7200 RPM SATA drive (1 TB Sun > badged Seagate ST31000N in a J4400) ? I have a resilver running and am > seeing about 700-800 writes/sec. on the hot spare as it resilvers. > There is no other I/O activity on this box, as this is a remote > replication target for production data. I have a the replication > disabled until the resilver completes. > > Solaris 10U9 > zpool version 22 > Server is a T2000 >
Here's how you calculate (average) how long a random IOPs takes: seek time + ((60 / RPMs) / 2))] A truly sequential IOPs is: (60 / RPMs) / 2) For that series of drives, seek time averages 8.5ms (per Seagate). So, you get 1 Random IOPs takes [8.5ms + 4.13ms] = 12.6ms, which translates to 78 IOPS 1 Sequential IOPs takes 4.13ms, which gives 120 IOPS. Note that due to averaging, the above numbers may be slightly higher or lower for any actual workload. In your case, since ZFS does write aggregation (turning multiple write requests into a single larger one), you might see what appears to be more than the above number from something like 'iostat', which is measuring not the *actual* writes to physical disk, but the *requested* write operations. -- Erik Trimble Java System Support Mailstop: usca22-317 Phone: x67195 Santa Clara, CA Timezone: US/Pacific (GMT-0800) _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
