On Fri, May 27, 2011 at 04:38:15PM +0400, Jim Klimov wrote: > And if the ZFS is supposedly smart enough to use request coalescing > as to minimize mechanical seek times, then it might actually be > possible that your disks would get "stuck" averagely serving requests > from different parts of the platter, i.e. middle-inside and middle-outside > and this might even be averagely more than 2x faster than a single > drive (due to non-zero track-to-track seek times).
In practice I've just found out I'm completely CPU-bound. Load goes to >11 during scrub, dd a large file causes ssh to crap out, etc. Completely unusable, in other words. So I think I'll try to go with a mirrored pool, and see whether the CPU load will go down. Maybe it's a FreeBSD (FreeNAS 8.0) brain damage, and things would have been better with OpenSolaris. I'll have to try the HP N36L setup to see what the CPU load with either raidz2 or mirrored pools will be. > This is purely my speculation, but now that I thought about it, can't get > rid of the idea ;) ... -- Eugen* Leitl <a href="http://leitl.org";>leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
