Good folders to exclude from Time Machine backups

Time Machine is a really effective tool for backing up everything on your drive. And when I say everything, I mean it — Time Machine indiscriminately backs up a lot of junk on your drive. And because of the techniques it uses and the way some files are used by your apps, you might find that your 500GB external backup drive is getting full after just a few months of use.

It’s really easy to identify folders for exclusion from Time Machine, which will save time and space during backups. It’s worth noting, though, that if your machine’s drive does fail, you won’t be able to execute a full restore without having some of these locations backed up. Then again, if you’re anything like me, you’re far more likely to just do a full reinstall and just restore your lost user data. (Doing a full restore from backup just doesn’t have many advantages compared to a full system reinstall, anyway.)

These are just a few suggestions — you should NEVER exclude anything from backup if you’re unsure you have another copy, aren’t able to get it again, or are unaware of the possible ramifications. Of course, you’ve got any good folders you think should be added to the list, feel free to drop ‘em in comments.

Obvious
The duh stuff.

• /Applications - This will likely save you more space than any other single folder, especially if you have lots of apps. Just make sure you know what programs you’d want to get back if your machine were to die.

Caches and downloads
Big directories of files that should probably be excluded automatically, but aren’t. Unless you’re a crazy developer debugging code, you’ll probably never need a backup of your caches.

• /Users/[user]/Library/Caches and /Library/Caches - Between the two you can knock off a few hundred megs of constantly changing, essentially useless data.
• /Users/[user]/Downloads - Where all your internet downloads wind up. Frequently changes, and if you’re anything like me, it’s filled with gigs of garbage.
• /Users/[user]/.Trash and /.Trashes - Some people might see value in backing up their trashed files. Not I.

More after the break. More…

Leopard: disable “Open with” previous versions of applications in Time Machine?

So Leopard does this really clever thing where, if you don’t exclude it from making backups of your Applications directory, it will let you do a right click / “open with” and select previous versions of apps Time Machine has backed up. The rub: you can’t turn it off, and if your Time Machine drive is connected but not spun up, it’ll wait until the drive gets going before populating that list and giving you the menu. Anyone discovered how to disable it (short of excluding the Applications directory from backup)?

Also, big ups to Conrad for sharing Stamatiou’s really useful OS X hack for turning off safe-sleep mode.