Talk about timing and bad luck, 3/4 the way through my install of Mountain Lion on an external drive, it died. The install crashed, the the drive would not mount to my MBP by way of FireWire, I tried disconnecting it there, (powering it down of course) and connecting it to my desktop through eSATA. Nothing would mount, this external drive is one of a cloned image of my internal drive but I also have it partitioned to hold my Lightroom library. I also back up my LightRoom library to the NAS as I don't want my images stored in on a single drive. I was less concerned about the failed ML install then rebuilding my library from the NAS backup. Thankfully after a praying and leaving it powered down or a while, I turned it back on and the it mounted. I'm in the process of refreshing my LightRoom backup The moral of the story - make sure you don't rely on a single back up method and make sure its current. I was sweating bullets because the backed up version is a bit old and while I had the images backed up elsewhere, it would have taken some work to rebuild the library. All this talk lately (mostly by me) of Aperture and LightRoom has me thinking about Aperture because I think its easier to manage separate Aperture libraries then doing this in LightRoom.