Linux server hangs, where to look for possible reason? [closed]

Kernel hangs are difficult to debug as no oops message is displayed on screen as in case of crash and if you are really lucky you will see something in /var/log/messages as during hang your entire system hangs along with syslog daemon and nothing will be write inside these files.

With that said hangs can be as simple as temporary performance issue caused due to memory or cpu contention,using inefficient algorithm or may be as complicated as deadlock.So like I mentioned above if you are really lucky

1: Check in /var/log/messages or may be run dmesg to get some pointer 2: If your system is hanging on regular basis then configure kdump along with sysrq keys to know the exact problem.

For more info please refer to http://people.redhat.com/anderson/crash_whitepaper/