Three things that, when mixed, can consume a surprising amount of disk space:
- Backup automatically with Time Machine
- Use iPhoto and take a lot of photos
- Sync photos to one or more iOS devices like iPhones and iPads
I do all three, and on top of that I have three current computers backing up to a 1GB Time Capsule. All of this combined was forcing Time Machine to expire old backups faster than I wanted as it churned through the disk space. Time Machine allows you to exclude specific files and folders from the backup, so the first thing I identified was the System folder. Upon selecting that, Time Machine will ask if you want to exclude other system files as well.
You really can’t do a bare meta restore with Time Machine, and there really shouldn’t be anything among those files except the stuff the OS installer disks and updaters put there, so there’s no reason to back them up. Saving those 13GB helps, but the real problem is the files that change frequently. For me, that means the contents of my iPhoto library. The iPhoto library contains a copy of every photo I keep, as well as edited versions of them, thumbnail previews, and downsized copies that get sync’d with my iPhone and iPad. There are a lot of little files in all that, they change frequently, and not all of them need to be backed up.
Here’s a view inside my iPhoto library:
The selected items are among those that don’t need to be backed up. How do I know they don’t need to be backed up? This Apple knowledge base article explains how to rebuild an iPhoto library that’s become corrupted. Holding down the Commant+Option keys while launching iPhoto will reveal this screen that allows you to select how you want to rebuild the library:
Selecting the two options to rebuild the thumbnails will recreate Previews and Thumbnails folders in the iPhoto Library. The iPod Photo Cache folder, meanwhile, will get recreated next time you sync your iOS device.
Back in my Time Machine preferences, this adds up to about 60GB of savings in the initial backup, and a whole lot less churn as I sync and manipulated my photos (Time Machine was saving a copy of every version of those thumbnails).
The result? My backups last longer before they expire and I can keep more copies of the files that really matter to me. That, and the backups go faster too.