The "other" memory section on my Mac is WAY too big.

Question

Hey everyone!
I know there are a LOT of discussions about this topic, but none of them really seemed to work for me. So the other day I got an error saying "Your startup disk is almost full". I immediately checked the storage section of "About my Mac", and sure enough, something like 100 GB were taken up by local backups. To fix this issue, I disabled local backups via this terminal command: sudo tmutil disablelocal.
I did a restart and checked my storage again. This time, it looked like this (and still does):
All of what used to be backups is now other. And the reason I have those 900 or so MB of backups is because I eventually turned those on again (with the reverse of the above command) in an effort to fix this. Out of options, I then went to the apple store, where they told me to just delete stuff that was too big. So I got a 1 TB drive and started copying and deleting stuff. The main thing I got rid of was a giant windows VM I had. And just to prove that something's wrong here, look at the breakdown of my files from OmniDiskSweeper:
If you do the math, I should have about 100 GB more free than I do now. I've tried:
Turning the thing off then on (you'd be surprised how often that works)
Resetting the PRAM
Forcing spotlight to reindex the machine
Throwing the machine out the window (well, not quite)
What I think might be the cause:
This is a stab in the dark here, but possibly all those GB of backups tried to delete themselves and somehow corrupted and aren not called backups anymore by the system?
Just one more thing: I noticed that OmniDiskSweeper showed a volume I don't recognize. It's called MobileBackups. Maybe that has something to do with it?
I'll appreciate your help.
Thanks!

Answer 1

Although the guide is a little dated, a lot of the information there is really great and helps you track down a lot of files that are just taking up way too much space on your hard drive.
http://pondini.org/OSX/DiskSpace.html
I just did this the other day on my Air running 10.9 and recovered around 50GB of disk space, so there is potentially a lot you can do. I suggest following the steps on this guide (to the T, don't want to mess anything up) and go from there. Don't delete ANYTHING that you are not aware of the function, and remember that searching for names of files is a great way to determine whether or not you need it. Some files that SEEM like junk and take up a considerable amount of space are system files that will either be replaced the next time you boot up or render you computer useless entirely.
For example, there is a file that saves the state of your computer just before it goes to sleep so that it can return quickly when you start up again, and that file is normally the size of the amount of RAM you have (I have 4GB of RAM, so the file was 4GB). After doing some research, this file will either be recreated if deleted, or your sleep mode will not be able to function properly if the file is deleted. So again, just tread lightly.
Also, there is an application I used to get rid of a bunch of duplicate files that I had on my drive called Gemini (http://macpaw.com/gemini), which I recommend using to clean up documents. Again, be careful, you don't want to go deleting files that you are using that the application mistook for a duplicate.
Hope this helps!