On Fri, Apr 18, 2008 at 8:28 AM, Bob Friesenhahn <[EMAIL PROTECTED]> wrote: > On Fri, 18 Apr 2008, Pascal Vandeputte wrote: > > > Thanks for all the replies! > > > > Some output from "iostat -x 1" while doing a dd of /dev/zero to a > > file on a raidz of c1t0d0s3, c1t1d0 and c1t2d0 using bs=1048576: > [ data removed ] > > > It's all a little fishy, and kw/s doesn't differ much between the > > drives (but this could be explained as drive(s) with longer wait > > queues holding back the others I guess?). > > Your data does strongly support my hypothesis that using a slice on > 'sd0' would slow down writes. It may also be that your boot drive is > a different type and vintage from the other drives.
ZFS disables (or rather, doesn't enable) the drive's write cache when it's using a slice. It can be manually enabled, however. The swap slice on your first disk is what's limiting your performance. > SATA drives are cheap this days so perhaps you can find a way to add a > fourth drive which is at least as good as the drives you are using for > c1t1d0 and c1t2d0. Using a separate boot volume with a swap slice on it might be a good idea. You'll be able to upgrade or reinstall your OS without touching the zpool. -B -- Brandon High [EMAIL PROTECTED] "The good is the enemy of the best." - Nietzsche _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
