Instant crash with ZFS + iozone?

[Jeremy Chadwick]

On Tue, May 04, 2010 at 01:22:35AM +0200, Lassi Tuura wrote:
> I installed 8.0-RELEASE, then 8.0-STABLE 201004 (amd64) on a system
> with 4 * 1TB hard drives for ZFS (2 * Hitachi Deskstar 7K2000, 2 *
> Samsung SpinPoint F3), plus 2GB IDE flash for OS itself (Transcend),
> 4GB ECC RAM, AMD Athlon II X2 235e CPU, Asus M4A78L-M LE motherboard.
> 
> I can use the basic system fine. However when I create a ZFS volume
> out of the 4 disks and run iozone on it, the system will reliably die
> within 5 seconds or so, sometimes it takes a little longer, up to a
> minute or so.
> 
> By "die" I mean the screen goes completely blank, and it will no
> longer respond to anything - no network, not even ping and any
> existing network connections will die, no keyboard, screen totally
> black without as much as a cursor... nothing. The soft power button
> won't work either. AFAIK the only thing that works is the reset
> button.

This sounds like a hardware problem to me -- particularly excessive draw
on the PSU, voltage issues, or other whatnots.  Especially if the screen
goes black (no cursor, monitor not in power save mode) and requires a
hard reset.  Possibly the problem is only witnessed under extreme disk
I/O combined with high CPU usage + memory I/O.

You might try removing some disks (drop it from 4 down to 2 and use a
ZFS mirror) and see if you can reproduce the problem.  If it doesn't
happen with 2 disks then my guess is what I described in the 1st
paragraph.

I would then advise trying to find a hardware stress test environment of
some sort (Linux may provide something like this; bootable CD which
beats on all the hardware simultaneously) and running it through that.
Windows has quite a few suites that do this as well.  Otherwise, replace
the mainboard and/or PSU (try one at a time) and see what happens.

If it is indeed a hardware problem, expect to spend time and money
trying to track down the root cause -- there's no easy way otherwise.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |