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CPanel Dedicated Server Nameserver Issues

Posted on 2013-01-22
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Last Modified: 2013-02-07
Hi -

My company has a dedicated server running CPanel that I have cursory involvement in - but only insofar as if something messes up it ends up falling into my lap to fix.  CPanel isn't my admin tool of choice - but I'm comfortable enough to navigate around in it.

The server is messing up - insofar as at some point - it gets bogged down (I'm assuming a ram issue?) and the nameserver functions start messing up (sites cease resolving).  So - I can't get to the server if I use the actual domain names - but I can get to it if I just use the direct IP of the server.

Now - I've got a couple of suspicions as to what's causing it - and I'd like your perspectives to see if I'm off base or if I'm probably on target.

Most likely cause (in my opinion)
Too many open/sleeping MySQL connections  - There's a site that exists off-server that communicates with the SQL server on ours.  When I look at the open MySQL processes - at some point it bogs up and there are HUNDREDS of open/sleeping MySQL processes going which have been open/sleeping for hours and hours.  

I'm thinking that the other service doesn't close the connections properly after each transaction - and eventually that just bogs down the server.

Secondary possible cause (in my opinion):
the /dev/sda1 partion is too full and there's too much memory swapping going on

/dev/sda1             9.7G  6.4G  2.8G  70% /

What do you think? Is this something you've run into before - and do my guesses sound on target?  Or is there something I might be missing.

Thanks!
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Question by:erzoolander
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Julian Matz earned 500 total points
ID: 38808573
Do you have root access? If so, what does the "top" command reveal? Also, if you install 'sysstat', it will give you some useful tools to monitor your server's resources over a period of time, which can be logged and then analyzed.

I've had many of these issues. In two instances, it was the hard drive, containing the root file system that was failing/corrupt. In another case, it was the MySQL server, which was getting bogged down by corrupt tables. There were a couple of other issues, too, so it really could be different reasons.

You can set cPanel to alert you when the server load reaches a certain threshold. If you then start an SSH session to your server and run the top command, it might give you a hint as to what's consuming your resources. You can install csf and lfd from www.configserver.com. It's a very simple process, and it ties in very nicely with cPanel. It is meant as firewall and intrusion prevention system, but it can also send you alerts such as the high server load alert. This may be easier than using the sysstat tools, although they are not that difficult either.

Another useful command is 'free -h', which shows you information about memory usage.
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