How to find the cause of a hang

[Greg 'groggy' Lehey]

On Saturday, 14 August 2004 at 12:17:31 +0200, Eirik verby wrote:
> Hi all,
>
> I'm currently experiencing frequent (about once per week) hangs of a
> server that is about 1500 kilometers away from me. I have a serial
> cable on the box, and using minicom on the neighbor box I am now in the
> kernel debugger - but I'm at a complete loss as to what to do to figure
> out what is, in fact, wrong.
>
> Calling panic or boot doesn't work - it just stops at "syncing
> disks..." and never actually reboots. I suspect something fishy going
> on with disk I/O, but I can't be certain of that.
> The box responds to ping - until I call panic or boot - but no other
> services are working.
>
> What can I do? I'm now at the db> prompt ... Help :)

Well, one possibility would be to debug online.  But dumping seems to
be broken on recent versions of -CURRENT--see my message on the topic
yesterday.  Try 'call doadump' instead of 'panic'.

Greg
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