So I have the 2012 (really 2013, hehe) and I bought the Seagate USB 3.0 flex drive. The problem this drive has, like many USB drives, is that it sleeps. I know, that saves energy and the life of the drive, but it also causes the computer to basically freeze when the drive springs back to life. Ordinarily it's not a big deal, but with time machine backing up every couple hours, it does pose an annoyance that web pages and everything else I'm doing pause for 3-5 seconds when the drive wakes up. edit: it also does the 3-5 second "spin up" every time my computer wakes, delaying my ability to input my password. Very annoying. Any suggestions for drives that don't suffer from this issue?