I’m a big fan of Time Machine. It’s not perfect, some like myself want to ensure they have an offsite backup as well, it doesn’t play perfectly with FileVault, and you can’t boot off the backup if you’re in a mission critical situation. Despite those few issues, with Time Machine, there’s no longer an excuse for not backing up all those digital family photos, extensive music collection, and rest of your digital life. If you haven’t been bitten yet… you will. It’s only a matter of time.

One of the frustrating things with Time Machine however can be the amount of space it starts to eat up on your external drive. Storage continues to get cheaper but I hate to toss my 500GB drive for something bigger just so I can let Time Machine do it’s thing.

Fortunately, there is a GREAT tool to help you squeeze the most out of your drive, GrandPerspective (VersionTracker, Main Site). GP is an excellent utility to graphically represent the space you’re using on disk. Better yet, it is smart enough to ignore the clever file referencing Time Machine uses to keep things in order, and in turn, can give you an accurate picture of your drive.

Just download the utility, and run it on your Backups.backupdb folder on your Time Machine drive, and you’ll quickly see if there are particularly large chunks being eaten up on your drive.

For me, GrandPerspective quickly identified a folder in Library/Application Support/Mozy which was eating up about 50% of my backup drive. It turned out, this was a temporary folder Mozy used to store files before they were uploaded to the Mozy backup server. Since this folder was always changing as Mozy gradually uploaded my system, Time Machine was dutifully preserving multiple versions of the contents of the folder every time it ran a backup. Blocking this folder from the Time Machine preferences has made my Time Machine backups far faster and far more space efficient which leaves more room for the important bits.

If you’re running out of space on your drive, give Grand Perspective a try.