Very interesting statistics that I’ve noticed since moving the site to a Linode VPS.
If you take a look at the graphic below, the spike in the middle will probably stick out quite a bit. Oddly enough, the spike I noticed in CPU percentage used (which is regulated for VPS at Linode) also spiked up disk usage…mainly because I began to swap when cpu/ram use skyrocketed. All of this happened with Ubuntu 10.04 installed. CentOS was the first distro I tried but I quickly switched to Ubuntu when I spotted a really nice how-to in the Linode document library. Oh, and please excuse my horrible gimp skills on the image below…it was a quick and dirty editing of the image:
After switching to Ubuntu, I began receiving alarms for my account due to the high usage of CPU and disk. I attempted to tweak settings and configuration files for about a week and realized it just wasn’t going to work for me. I switched to Debian Lenny and the move was a positive as is reflected in these pictures.
I was hoping Ubuntu 10.04 would fit for me since it is a long term support (LTS) release. CentOS is my normal server distribution of choice and I really wanted to branch out and go with something different. I used a Linode Stackscript for WordPress for CentOS but elected for vanilla installs of Ubuntu and Debian aftwards (I didn’t like NOT knowing what was installed when I first logged in…call me a control freak).
I just found it interesting that Ubuntu 10.04 did so horribly in this instance. After investigating, I found a couple of likely suspects:
- Default Apache install in Ubuntu leaves a lot to be desired..even after tweaking both it and PHP for days I couldn’t get them to lay off the resources. Even switching to mpm_worker and FastCGI did little to settle things down.
- Ubuntu swappiness is bad…it is set at 60 (I use 10 normally) and it swapped every chance it could get…it’s set by default to swap more than it should.
- mod_php on Ubuntu is hungry for all your cpu and ram and disk; be warned!
Debian, as the parent distribution of Ubuntu, would most likely suffer from the same problems…except it doesn’t. Things are working great with it and I’d recommend it for any of your server needs! Has anyone else seen this oddity with Ubuntu 10.04? If so, please drop me a comment below.
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