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panic crash (hardware troubleshooting ideas)

Weak power supplies can cause odd problems - crashes and freezes.

Memory is cheap and usually the quickest and easiest thing to replace unless you have one of those awful machines where a whole bunch of other stuff has to come out before you can get near the mother board.

Replacing cables is also relatively easy, though again some designs have things snaking through this and that.

Replacing a motherboard is much more time consuming. I've bought brand new machines rather than go through that (less downtime, less stress).

From: "Brian K. White" <brian@aljex.com>
Newsgroups: comp.unix.sco.misc
Subject: Re: Unix 5.0 in panic
        charset="Windows-1252"
X-MSMail-Priority: Normal
X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700
Message-ID: <pAVn7.10699$tL2.1016104@news1.rdc1.nj.home.com> 
Date: Thu, 13 Sep 2001 03:18:45 GMT


> > > > unix stopped using following message:
> > > > unexpected trap in kernel mode:
> > > > PANIC: k_trap - kernel mode trap type 0x00000160
> > > > trying to dump 16287 pages to dumpdev hd (1/41) at block 0, 204 pages
>
> Finally: to my (limited) experience, this kind of trouble
> is very hard to diagnosticize. If it doesn't come back
> within a month of continuous operation, just forget it.
> If it does, I think you ought to suspect hardware, and
> start by swapping step for step, starting with memory
> (easiest and cheapest), next CPU, next motherboard.

While the memory might be the easiest and cheapest thing to replace, it is
among the least likely to change with age. The most likely peice of hardware
to look at for random problems after years of no problems, (barring the
obvious, cpu and powersupply fans) is the power supply.

if the power supply doesn't fix it, then all other components are about
equally likely, but I'd start with the motherboard (it has capacitors that
change value with age, as do some other components, but a dead cdrom drive
generally doesn't affect the rest of the system)

One thing I've seen, if the motherboard is old, try upping the voltage on
the cpu by 1 or 2 tenths of a volt. I have seen this work. I don't know
which of two most probable reasons it works. maybe a) the chip is "old" and
has changed inside, and now needs a higher voltage to work reliably.  or
maybe b) the motherboard is "old" and when you set the jumpers for say, 2.9
volts, it's no longer actually delivering that, so you need to set it to
say, 3.1, to get 2.9. Either way, if this seems to fix the problem, do 2
things immediately. 1) install a new, oversized cpu fan and heat sink, and
use heatsink grease and remove any stickers or other foreign objects between
the cpu face and the heat sink. 2) tell the owner of the computer to be
ready to replace the server because this only buys you some time, it cannot
be considered a real fix.

Another thing I've seen more than once: scsi ribbon cables that touch metal,
where the insulation has worn away and the wire inside is just barely
visible, meaning it sometimes but not always gets shorted to the chassis
ground. You have to look close and careful for that, not just near sharp
corners either. Systems run mostly ok, but get a random corrupted file here
and there and messages in the log file and sometimes momentary server lockup
or even unexpected reboot. Basically, If you see symptoms that make you
think "hard drive is going south", look hard at the cable first.

--
Brian K. White  --  brian@aljex.com  --  http://www.aljex.com/bkw/
+++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
filePro BBx  Linux SCO  Prosper/FACTS AutoCAD  #callahans Satriani

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