So I came back to my computer to the BIOS saying "Loading Operating System". Waiting did nothing, and resetting would only get me to the same screen and still not progress past it. I unplugged the 2 mirrored HDDs (let's call them A1 and A2, since they were both the A: drive) and left C: plugged in, and it booted fine. When I plugged A1 and A2 back in, it then booted and they were both recognized as disks in Disk Management, however, all was not right. Ignoring C:, there were 4 entries: 2 "missing", and the 2 disks themselves (I forget what it labeled them as). So I tried assigning one for the disks to A: which resulted in that disk entry and 1 missing entry disappearing and being replaced by A:. I did the same for the other disk, but A: was unavailable from the drive letter list, and no other relevant options were available, so I just chose another drive letter (F:). I hoped that there would then be an option to tell Disk Management that these two drives (A: and F:) are really supposed to be mirrors (just A:) and that they'd easily resynchronize, but that option isn't available. Is there something I'm missing? Since they're really 100% the same, I was hoping for an option that won't require all the data to be read/written again, adding unnecessary wear to the HDDs. Any advice? Thanks.