On Mon, 2010-10-18 at 17:32 -0400, Edward Ned Harvey wrote: > > From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > > boun...@opensolaris.org] On Behalf Of Marty Scholes > > > > Would it make sense for scrub/resilver to be more aware of operating in > > disk order instead of zfs order? > > It would certainly make sense. As mentioned, even if you do the entire disk > this way, including unused space, it is faster than making the poor little > disks randomly seek all over the place for tiny little fragments that > eventually add up to a significant portion of the whole disk. > > The main question is: How difficult would it be to implement? > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Ideally, you want the best of both worlds: ZFS is currently *much* faster when doing partial resyncs (i.e. updating stale drives) by using the walk-the-metadata-tree method. However, it would be nice to have it recognize when a full disk rebuild is required, and switch to some form of a full disk sequential copy. The problem with a full sequential copy is threefold, however: (a) you (often) copy a whole lots of bits that aren't actually holding any valuable info (b) it can get a little tricky distinguishing between the case of an interrupted full-disk resilver and a freshen-the-stale-drive resilver. (c) You generally punt on any advantage of knowing how the pool is structured. Frankly, if I could ever figure out when the mythical BP rewrite (or equivalent feature) will appear, I'd be able to implement a defragger (or, maybe, a "compactor" is a better term). Having a defrag util keep the zpool relatively compacted would seriously reduce the work in a resilver. -- 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
