I'm needing more physical free space on my desk, so I'm letting my 2009 21" 1 terabyte iMac go and have bought a 13" 256 gig rMBP (refurbished). I'm looking for migration advice and how best to solve the problem of having a quarter of the hard drive I have now. I have previously used time machine to back-up the iMac (however that back-up drive conked out a month ago). Files wise, I've got about 600 gigs total with iTunes taking up the largest chunk at probably close to 300 gigs. iPhoto, mail, photos, documents, etc. are the rest of the bulk. Basically, what I feel like I should have is a drive that I 'run' all the large chunks off of (i.e. iTunes, iPhoto, mail-?, all the folders of documents and other stuff, etc.) and then I'll keep only primary and necessary files/documents on my physical computer, the rMBP, that I'd need access to while on the go. And then I'd like a new drive that is the 'back-up' time machine drive as well incase the drive I'm running things off of crashes. I'm wondering how exactly to go about this without losing all my preferences, playlists, mail, etc. I can't seem to find info on how to do this specifically. Suggestions? Thoughts? I'm not a super tech type of person. Time machine back-ups are easy enough, but this is a whole other ballgame for me.