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Seems today a website I manage has been going online and offline between 12a and 12:25a. I have no idea what is causing the issue so I am seeking guidance on where to start. It is a Wordpress based site.

So here is what I DO know:

I have a pingdom account which alerts me when the site goes offline so we can see every day, like clockwork, the site goes on/off.

At the time of the ups/downs I see a lot of strain on the memory usage. Look at the load average when the site is going online/offline (http://screencast.com/t/BRlfXkqrbJII). Then I ran this command to restart http (http://screencast.com/t/usVtYWZ2Qi) and the memory usage then goes down to this (http://screencast.com/t/VdTIy3bgZiQB). An hour after I restarted http, the site then went offline/online so restarting the http didn't do much help.

When the site is going offline/online, I ran the top command and get this (http://screencast.com/t/zEwr7YQj3). Here is a top command when the site is at it's lowest (http://screencast.com/t/eaMfha9lbT - so this would be dubbged "normal").

Here is a bandwidth report (http://screencast.com/t/AS0h2CH1Gypq).

The traffic doesn't seem to be that much (http://screencast.com/t/s7hrWNNic1K), but looking at my times the site is going up/down this may be one of the reasons?

I have the dvp Nitro package at Media Temple (http://mediatemple.net/webhosting/nitro/).

So at this point I would request some help in trying to figure out what the cause of this is, and how I can go about pinpointing this issue. ANY HELP is greatly appreciated.