My home server, which happily houses 8 years of kids' photos, all our 'shared' files, music, etc...had a hard drive failure over the past few weeks. I finally got around to replacing the drive, which required me to dive into the use of mdadm deeper than I had before. In the end, it was all good. Two articles that ended up being the most helpful, to get me past sticking points: Getting access to the failed RAID from a Live CD: http://www.jeffsplace.net/node/14There are plenty of articles on replacing the failed drive, but this one also included the tidbit of installing Grub into the MBR of the new drive...that was the critical last step for me: http://www.kernelhardware.org/replacing-failed-raid-drive/