I currently plan on picking up 2 new drives now. One to replace the dead drive, and the second I'm not sure what would be best to do with. If I should install the second drive after the first drive is rebuilt or wait until a second drive dies to replace it or until I have enough drives to fully replace the array. My thought is if I wait till a second drive fails then I would be replacing the next drive likely to fail. Whereas by replacing a random drive the new drive that drive might not be the next drive to fail.