I am sure of the answer but just want to double check. We have had a bad drive in a MD1220 for a while but
for some reason it never got replaced. Now we have a hard failure in that upon reboot of the server the BIOS complains that "a disk has been removed or is inaccssible.." or something to that effect. I ordered a new drive and expect it tomorrow. I would assume that I just need to pop the old one out and the other back in and it will rebuild. I absolutely hope it rebuils and I did not lose anything or else we are in a bit of trouble. And just don't ask the backup question.
Note Windows also pretty much "lost" the logical drive as it shows up in computer management as "unallocated" and "unknowm".