Thought I would just write a quick post for people considering buying a large ssd (>256gb) for booting from a seagate thunderbolt adapter (STAE121 etc). I originally had a 256gb M4 booting from the seagate portable thunderbolt adapter (http://www.amazon.com/Seagate-GoFle...e=UTF8&qid=1360151662&sr=8-1&keywords=stae121) with absolutely no issues. I then came across a 512gb m4 going quite cheap so bought it and tried in the adapter. The drive would mount but whenever I tried to do anything with it, the drive would break and be unmountable again. I spoke with Crucial and they didn't seem to be able to sort the problem so they sent a replacement drive. The exact same thing happened with the new drive which suggested that the problem wasn't with the drive. After a lot of googling, I came across the blog post http://wolfgangtechnology.blogspot.co.uk/2012/06/mac-with-seagate-thunderbolt-adapter.html which seems to suggest that thunderbolt alone does not supply enough power for large ssds. With this in mind a fresh drive from Crucial I bought this adapter, http://store.apple.com/uk/product/H...x-thunderbolt-adapter-for-desktop-hard-drives which comes with a power supply. Since then I have had absolutely no issues with the 512gb m4 drive. Hope this will be of use to anyone considering purchasing a thunderbolt caddy in the future.