[CentOS] How to determine why a server is not responding

Thu Apr 11 16:04:23 UTC 2013
Александр Кириллов <nevis2us at infoline.su>

> We're using CentOS 5.5 64bits for our Plesk 11.
> This week we had the following problem 3 times...
> Suddenly, the server stops responding in all services (SSH, Apache,
> Postfix, ...) but ping works!
> After wait a few minutes (or 2 hours some times) the server continues
> unresponsive until we reboot. After reboot we search on 
> /var/log/messages
> but cannot find useful information...


> What can we do? what can we test?

Could be something related to disk access or RAM, runaway process or 
Do you have any system monitoring tools installed? Like munin, atop, 
Any kernel errors in the logs?