At ONLamp.com, Robert Jones has lots of good advice for Planning for Disaster Recovery on LAMP Systems:

"Don't get me wrong, disaster recovery is a critical issue. It's just that it can be a very painful process for those of us who come from an informal development background. [...] I know I'm not the only one dealing with this issue so here are some ideas that you might want to build into your apps.

The problem with our sort of database applications is that they weave themselves into the Linux system configuration. We add definition blocks to the configuration files for Apache, MySQL, Samba, et al. We create system-wide environment variables in user shells and insert symbolic links into the filesystem. Every time we rebuild a system we have to make the configuration changes anew. The potential for error is large, even assuming we remember all the steps."