Mark | On 30, Jul 2011

Having never really used Time Machine before now I thought it was high time that I put the spare HDD I have lying about to use. Well more like I’m debating formatting my system to do a clean install of Lion and wanted a local backup for a change.

Looking around the net for information, here are my recommended area’s to exclude from Time Machine Backups.

Note in Lion you will need to Unhide your /Users/[user]/Library/ folder. Our guide to do that is here.

To unhide areas in mountain Lion open terminal and enter

defaults write com.apple.Finder AppleShowAllFiles YES

/Applications

– My tactic here was to let time machine do a one time back up for this area and then select it to be excluded.  This will save you a heap of space to say the least but remember to keep the installers for those hard to find programs

Caches and downloads
Browsing the net can leave you with a whole host of crazy files that add to time machine’s duties.  There’s not real need to keep them unless you are a mad programmer so let’s exclude those as well.

/Users/[user]/Library/Caches and /Library/Caches –
Between the two you can knock off a few hundred megs of constantly changing, essentially useless data (for example: all the page caches from Firefox).

/Users/[user]/Downloads – Half the time I just download and forget about it.  Excluding this will save you space and time with your backups.

/Library/Mail Downloads - Mail attachments can be a pesky one and can easily grow in size.  I tend to use IMAP on my mail server.

/Users/[user]/.Trash and /.Trashes – A tricky one this, however if you have trashed a file there’s going to be the original on a previous backup.  Trash is that, trash, so it can be excluded especially if you end up deleting movies and tv show’s etc.

Audio and media
Use EyeTV or a similar TV Tuner? then DONT FORGET to exclude your recording directory.  It’s a little strange to see 20gb’s of backups happening all day, everyday, as you are backing up TV show’s EVERY time.  So look to where your recording directory is and, for the love of god and hard disk space, exclude that.

Some more obvious picks.

/Library/Audio – You can save from the hundreds of megs to gigs here. Keep an eye out for the GarageBand samples, they weigh a ton.

/Users/[user]/Music/iTunes/iTunes Music/Podcasts – Aside from keeping the odd podcast, for me they are a one time listen as they can easily be re downloaded.

Time Machine un-friendly apps
The data produced by some of these apps can easily be the worst offenders when it comes to backups. Until they get their act together, they should likely be excluded categorically.

Parallels (/Users/[user]/Library/Parallels) and VMware (/Users/[user]/Documents/Virtual Machines)- You’ll definitely want to keep a copy of your virtual machines, but if left included in Time Machine backups, your system will continuously save the virtual disks each time you use Parallels or VMware. (VMware has become a little more TM-aware though, which is good.) That means potentially hundreds of wasted GB — not to mention tons of lost time during backup.

Entourage (/Users/[user]/Documents/Microsoft User Data/Office 2008 Identities) –
Same deal here, Entourage uses one giant, constantly changing file to store all your mail. It sucks not to have your email backed up though, so be sure to use something other than Time Machine for keeping a copy handy in case of emergency.

/Users/[user]/Library/Mail Downloads – Whenever you open an attachment in Mail, it stores a copy of the file in your Mail.app attachments folder. If you’re a heavy Mail user, excluding this will save you some real space.

Other Ways To Save Space For Your Time Machine Backups

Do you need to Backup Your iTunes Library?

It’s one that can often be forgotten but also takes up a huge chunk of space, especially if you have movies.  iTunes match would mean you have a copy of your tunes up in the cloud ready for pulling down when you need.

How To Find Big Files and Folders To Exclude.

So you followed this guide and think you got it covered but something is still causing your backups to go wild.  Use a disk sweeper program like Omnidisk.  Omnidisk will scan your entire hard drive, showing you sizes of directories.  That’ll guide you in the right direction of anything too large and doesn’t need backing up.