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From: Lassi Tuura <lat@cern.ch>
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To: Jeremy Chadwick <freebsd@jdc.parodius.com>
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Subject: Re: Instant crash with ZFS + iozone?
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Hi,

> 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.

Thanks, that does look like plausible explanation here. I'll see what I
can do. As you suggested, I made some tests with various number of disks
and read/write patterns; ZFS is totally peripheral to this, I can get dd
to induce similar failures. Two drives is ok, three only if there's not
a lot of seeking, four only if two are reading and two are writing
sequentially (no seeking at all). Selectively taking drives out and/or
rearranging drives doesn't change this - it's not an issue with any one
drive that I can tell - so will focus on PSU next.

(Re Josh' reply I was in fact running iozone as root. Will keep in mind.)

Regards,
Lassi