I was recently having a problem where my new computer was becoming extremely sluggish while running Ubuntu Linux 11.04. The keyboard input was very delayed and slow. The graphics were terribly slow. Just about everything in the system became very slow. I've heard reports from similar problems, of complete lockups. It seemed to be linked to when the screensaver was activated, or power management was activated. But, after having disabled both, and continuing to have problems, I realized that wasn't it. Keep reading for the solution to my problem; I hope it helps you too.
Well, I've had a lot of trouble switching my system from LVM, to RAID1+LVM on ubuntu 10.04. I got another drive for my system, created a mirror with one drive (temporarily of course) asked lvm to move my entire system over to that physical device, added the previous drive to the raid array, and rebooted (oops). I am listing a few things that are important to know when you're both new to Ubuntu, and doing raid post installation of Ubuntu.