I encountered a rather strange issue on one of MySapients CentOS 5 servers the other day, the server seemed to run fine, without any issues what so ever, but it seem to run very low on memory. In fact it only had 150MB memory available of a total 4GB.

This obviously caused me a bit of a worry, but after some digging around I found the answer, linux is borrowing unused memory to do disk caching. Memory is automatically reassigned when the server needs to allocate memory to other services, in other words there is nothing to worry about.

There is a good site about this describing this functionality in more detail, you can read it at:

http://www.linuxatemyram.com/

Yesterday I installed the openbook plugin for wordpress on this site. My intentions was to build a “My bookshelf” page similar to what Mats Lindh and Trond Huso have on their sites.

I installed the plugin without any problems but the layout was a bit nasty. I don’t know if that was because of the theme I am running on this site or if the openbook markup was messed up. Anyway I rewrote the html and css for the openbooks template on its configuration page and added some custom css to the site to get it working.

This is my openbook template:

This is a great article describing super columns and the general structure of cassandra. A must read for NoSQL newbies.

http://arin.me/code/wtf-is-a-supercolumn-cassandra-data-model