[NCLUG] sw raid, recovery after install

[Sean Reifschneider]

On 01/17/2013 04:20 AM, Michael Milligan wrote:
> I've noticed the same thing, even with ARC tuning.  Scrub speeds don't
> seem to be related to array size or # of drives, not in any expected way.

I'm pretty sure that the scrub bypasses the ARC and L2ARC, because it's
whole purpose is to verify what is on disc...

The discs do, IIRC, go to high utilization in iostat, throughout the scrub.
For example, see the munin graphs at:

   http://jafo.tummy.com/zfs-utilization.png

That's during that 140+ hour scrub.

> That's the danger of not using full drives for RAID5 (or even RAID6) arrays.

Yeah, that's pretty risky.  At that point you almost might as well be using
striping.

Sean