I recently had an absolute nightmare where I was streaming over my network from my MBP 2012 to my ATV 3, simply playing videos from my itunes playlist. It then all of a sudden cut out, and I tried switching my mac back on but it kept dying after the boot logo. So I tried dumping PRAM, booting into recovery etc. It was then I notice that the HD (my 320gb Hitachi HDD which came with the mac originally) was displayed as connected but the one and only partition was displaying as unmounted, and would allow me to erase it, nor would it allow me to do anything. I attempted verifying (which came back as OK) and repair (which was the same) both of these I've repeated countless times. Also I tried disconnecting the HD and then putting it all back together but this made absolutely no difference. Either way I used this as an excuse to upgrade to an SSD, which is running fine and is now running mavericks etc. The problem I'm having is that I want to transfer some of my old data (i.e. films, and 4 years worth of art work) onto my SSD, erase the old HDD and use it as a portable backup as it's now in a caddy. However I'm unable to access any files, it's displaying exactly the same as when it was originally inside my mac. I've included a screen shot of the Disc Utility screen and a couple of the error messages I'm recieving. I'm beginning to give up hope that I'll be able to access my files which is a bit heartbreaking, most of it is backed up online in some way or another so it's not the end of the world, however I'd really like to use the HDD, it spins perfectly, no clicks, no issues at all, and as you can see from the images it's being read. Any help/ideas would be really appreciated.