Mac Geekery

Answer

Mac OS X itself doesn’t really take up much space at all. The Darwin components, mostly installed in /private, weighs in at a few hundred megabytes. Your private probably looks like it takes up a gig or two, but most of that is from /var/vm, which contains your virtual memory swapfiles.

The “Mac” part of Mac OS X is stored in /System and, on most systems, pulls up at about 2GB. The biggest part of /System is /System/Library/Frameworks, which is a collection of libraries that Mac OS X applications use to work. Now, you don’t strictly need all of these frameworks, but you need most of them, and the only ones of any significant girth are all fairly essential. Outside of Frameworks, there’s not really much left that you can junk safely and, of what you can, none really amounts to enough space to bother.

That doesn’t mean there’s nothing you can do, though. Apple installs lots of preloaded software on your machine, some of which is fairly hefty. The biggest offenders are Garage Band and iDVD. If you can live without these apps, you can look in /Library/Application Support and junk most of their support files. Garange Band, particularly, stores several gigs of loops and instruments here. My /Library, sans Garage Band and iDVD, weighs in at 6.12GB. The iMac in the next office is only 600MB.

The root level Library folder, it turns out, is mostly ancilliary files. Very little here is truly needed for your computer to boot and run, strictly speaking. The two major exceptions are /Library/Keychains and /Library/Fonts, the deletion of which can cause myriad and sundry problems you might be able to guess.

That said, I would not go merrily chunking the majority of these folders or their contents. Sort the guy by size and investigate major offenders, throwing away only files that belong to applications you do not expect to use.

WhatSize is a great tool to delve into what’s taking so much space on your drive and where. Monolingual is another great tool that allows you to remove languages from the system that you don’t speak or don’t need available on the computer, saving a moderate amount of space. Be careful about culling PPC code on Intel machines with Monolingual, though, as this will bust Rosetta.