What is best method to debug freezes/hangs?
derek at computinginnovations.com
Wed Dec 5 04:17:19 PST 2007
At 08:49 PM 12/4/2007, yar wrote:
>My question is how best to go about debugging sporadic freezes and hangs.
>Just looking for general methods. On a couple of our IDS systems there
>are sporadic hangs or freezes that occur every couple weeks or so, that are
>recoverable by either system reboots or taking out and reinserting the Gig
>fiber ethernet sniffing cables, but I never can find anything in
>/var/logs/messages to tell what is going on. I'm assuming that may have to
>compile in kernel debugger support, but from what I read briefly, doesn't
>that require an actual crash with the resultant reboot and a debugger
>readable file left in /var/crash? That doesn't happen, there is no
>automatic reboot just a freeze/hang (box falls off network and at the
>console unable to type until one of the two above mentioned measures are
>take. The systems are:
>Free BSD 6.2
>2 Gb ram
>running various open source IDS software BRO
I would be sure your systems are running the generic kernel, or as close to
generic that is possible to rule out anything you could have introduced by
running a custom kernel.
I would also run complete diagnostics on the hardware to rule out any
You can also gather some information by having a script run top
periodically and logging this to a file to see what the system is
doing. You can check the last log entry of this file after a freeze/hang
to see what was going on.
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