[CentOS] Diagnosing random hangs

Mon Dec 18 21:54:24 UTC 2006
John R Pierce <pierce at hogranch.com>

Mark Belanger wrote:
> Matthew Miller wrote:
>> On Mon, Dec 18, 2006 at 04:17:59PM -0500, Mark Belanger wrote:
>>> I have many different centos machines that are hanging
>>> regulary.  I believe this is due to something our application
>>> is doing - not a centos specific problem.
>>> When the machines hang, there is no access to the console
>>> or remote access(ssh, rsh, etc).
>> Do you mean that there's no *access* to the console, or that it doesn't
>> *respond* on the console?
> X is frozen, no way to switch the console(i.e. Ctrl-Alt-F1, 
> Ctrl-Alt-Backspace),
> and no way to access the machine remotely.

if you don't need X running, I'd stop loading it entirely (edit 
/etc/inittab, and change the default runlevel to 3), and before your app 
hangs, log onto the system console, and leave this command running as 

# tail -f /var/log/messages /var/log/secure

this way, any error logging will be displayed as the system crashes.