On Mon, Feb 14, 2011 at 03:04:18PM -0500, Paul Kraus wrote: > On Mon, Feb 14, 2011 at 2:38 PM, Gary Mills <mi...@cc.umanitoba.ca> wrote: > > > > Is there any reason not to use one LUN per RAID group? [...] > In other words, if you build a zpool with one vdev of 10GB and > another with two vdev's each of 5GB (both coming from the same array > and raid set) you get almost exactly twice the random read performance > from the 2x5 zpool vs. the 1x10 zpool.
This finding is surprising to me. How do you explain it? Is it simply that you get twice as many outstanding I/O requests with two LUNs? Is it limited by the default I/O queue depth in ZFS? After all, all of the I/O requests must be handled by the same RAID group once they reach the storage device. > Also, using a 2540 disk array setup as a 10 disk RAID6 (with 2 hot > spares), you get substantially better random read performance using 10 > LUNs vs. 1 LUN. While inconvenient, this just reflects the scaling of > ZFS aith number of vdevs and not "spindles". -- -Gary Mills- -Unix Group- -Computer and Network Services- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
