Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

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

I am not a sys admin, I just play one occasionally for clients. I'm a developer, and usually look for the easiest solutions available for deploying applications. I have a dedicated virtual web server at using CentOS and Plesk.

For the last two days it's been absolutely slow as can be and I have no idea why. Traffic is low if anything and everything on the application end checks out okay.

How do I figure out what else could be causing the slowness? I apologize for such a generic question, but I haven't the faintest of where to begin. I'm not sure what I should or shouldn't be looking at given that this is hosted on a virtual server.

I do have SSH access so I can muck around in there. Where should I check my web server for potential bottlenecks?

share|improve this question
I'm a bit confused by the idea of a 'dedicated, virtual' server. Aren't those contradictory? – romandas Sep 8 '09 at 19:38
It means you get a guaranteed reserved set of memory for a virtual server instead of shared – andybaird Sep 15 '09 at 13:33
up vote 3 down vote accepted

Start w/ the basics: top will give you an idea of some user-land process has run away with memory or CPU. I'm not familiar with's virtualization offerings, but there shouldn't be anything that you "shouldn't" look at inside the VM.

You say "everything on the application end checks out okay". Does that mean that you've executed the application locally on the server computer (running the PHP scripts from a command line, for example, on a PHP-based site) and that they're running as quickly as you'd expect? If so, that pretty well limits the problem to being a network bandwidth / latency issue. If you haven't done that, give it a try.

How does a "traceroute" between the client computers and the server look? Any long delays along the way?

share|improve this answer
top is incredibly useful, thanks! No major memory usage, though. MySQL occassionally pops up to the top with 1% CPU usage. Only half of memory in total is used. Traceroute was very fast (59ms on average) whereas page loads are taking in excess of 7 - 10 seconds. – andybaird Jul 6 '09 at 16:36

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.