HELP: Question about partitioning external drive

I have a 500 mb external drive that I've been using for Time Machine since around this past Christmas, though I've probably only used it about 10-20 times.

Anyways, I have about 230 GB of audio on my macbook pro (without retina) and including the other stuff on my hard drive I only have about 7 GB free out of 319 GB and my computer is painfully slow. I decided to subscribe to iTunes Match a few weeks ago but I had been having problems with it until earlier tonight so I'm afraid to delete the music off of my computer and even if i did I would want a backup of it all just to be safe, so I was thinking about partitioning my external hard drive and making around 250-275 GB (library is always growing) to store/backup my music collection and then just use the remaining space on it for Time Machine.

The only problem is that I have never done it before and basically have no idea how to partition my external drive and I feel like I'll somehow manage to screw it up and lose all my music. From what I have read about it so far, you just have to go into disk utilities and select your external drive, go to partition, then divide it up into however many partitions you want and assign the size to the partitions and then hit apply. (please correct/enlighten me if I'm wrong)

Right now, my external drive has a little over 400 GB of backups on it and I'm concerned/unsure what will happen to the backups on it if I partition over them.

I guess I'm just basically looking for some suggestions/thoughts/guidance on what I should do. I would take just take my problem to a Genius Bar but the closest one to my school is a 30 min car drive away...and I don't have a car.


NOTE: I created my account here less than an hour ago so I apologize in advance for any rookie mistakes & if there are any let me know

I would assume your external drive is 500 GB (vs mb).

You def need to get some free space on that drive and defrag it at this point - if you're going to keep it in the machine.
No reason to be unsure - If you create a 200+ GB partition on your external that already has 400GB of data out of 500 GB - you will lose all the data on that drive.

Frankly, there does not exist a real solution for you that does not involve spending some cash. By real solution, I mean having plenty of free space on your internal drive so that the operating system can function properly and having all of your data backed up to at least one place. You simply do not have enough drive space for the amount of data you want to keep - it's time to get more.

What I would do in your situation - particularly in light of your ever growing music collection - replace the internal drive with a WD Black 750 GB drive - just get the WD7500BPKX version - $70 at Amazon. Clone your existing drive to it and pop it into your MBP. You'll also find it faster than the drive that came with your MBP.

The above is a minimum - that gives you all your music on your computer and over 50% free space which should keep you going for awhile. Keep using TM to back up to your existing external and use the drive you've removed from the MBP to create a 2nd backup of your music library.

As your library grows, you will need a new and larger external drive(s) for your backups.

When your library starts reaching 500GB or more, at that time you'll have to start looking at keeping your music/videos on external drives.
Typically meaning looking at RAID set ups or a minimum of 3 external drives in order to keep everything backed up adequately.

Oh, and never let your system drive - the one that you are booting the computer from go under 15% free space - and if you want to keep the OS running as fast as possible, you need 30% free and defrag the drive on occasion as the free space becomes fragmented.