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Date: Mon, 20 Mar 2017 03:04:40 +1100 (EST)
From: Ian Smith <smithi@nimnet.asn.au>
To: Bertram Scharpf <lists@bertram-scharpf.de>
cc: CeDeROM <cederom@tlen.pl>, freebsd-questions@freebsd.org
Subject: Re: Second severe crash in six weeks
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In freebsd-questions Digest, Vol 667, Issue 9, Message: 7
On Sun, 19 Mar 2017 12:46:52 +0100 Bertram Scharpf <lists@bertram-scharpf.de> wrote:
 > On Friday, 17. Mar 2017, 22:58:32 +0100, CeDeROM wrote:
 > > Bertam, are you sure you are working on a clean filesystem? Did you
 > > run FSCK -F / from single user as suggested??
 > 
 > Didn't help.

Bertram, everything about your various issues suggests hardware to me.

Memory is usually the first thing to check, but all sorts of components 
can go flaky, sometimes in almost non-deterministic (ie, weird) ways.

Have you tried the suggested memtest86 test, for at least an hour or so?

Another useful tester is sysutils/stress, which may be installed and run 
without rebooting or other inconvenience.  Something like:

 # stress -c 2 -t 1200 &

will run 2 CPUs at 100% for 20 minutes in background; adjust to >= cpu 
count.  Meanwhile keep an eye on system temperatures and fans; this gets 
CPU/s as hot as they can.  Your system should be engineered to cope with 
running at full rated load, with some headroom.

cheers, Ian