Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

My production server is running Apache v2.2.4 with mod_mono v1.2.4 on CentOS release 5.2 (Final).

Suddenly, Apache service hung during normal usage time (approx. 1 pm EDT). Traffic is not too high at this time. This is the first time we're noticing this kind of behaviour in our server. I noticed from access log that even subsequent requests are also not received, even though there were incoming requests. I then manually tried to invoke my application call from web browser, it never returned successfully but it was still loading.

I found no unusual behaviour/activity in:
1) Apache access_log and error_log
2) No kernel level errors found in /var/log/messages

I've no other option but ended up restarting Apache service.

Any idea on what would cause Apache to hang and thereby not allowing subsequent incoming requests? How do I debug/diagnose when this happens next time?

Experts advice/recommendation on this are highly appreciated.

share|improve this question

I have encountered this when there is a block on IO in the kernel. Is the Apache perhaps serving data from an NFS mount or something similar that can fail hard?

share|improve this answer
In my case, I don't think this is a block in IO. Regarding serving of data, my Apache is serving data from within my server drive which is attached permanently, and this is not a NFS mount. – Gnanam Jun 18 '10 at 9:05

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.