Software RAID under Linux is a rock solid solution for building RAID arrays at no cost. I personnally never had problems with software raid under Linux while i've seen expensive hardware RAID card failing and corrupting arrays. It's a little slower that hardware RAID but it remove a possible point of failure in a system and again, it's free. The only drawback is that configuration can be sometimes tricky. This guide is a collection of command you can use in different situation.

In this howto we will install Ubuntu in RAID 1 and I will explain you how to manage your array using mdadm. Tested on Ubuntu 8.04 LTS and 8.10 (both server version).