I've got 2 time machine drives. I have one at home that gets used on the weekend and another that gets backed up to during the week. I recently replaced the one at my office. The only thing that is weird is that it's backing up 3-4GB of data each hour. It goes super quick, so it doesn't feel like its actually backing up that much data, though. I've ran disk utility on the disk and it doesn't find anything. Any thoughts? Is it just something weird or is there a problem with the drive?


2 Answers 2


On Lion you can use tmutil to compare Time Machine backups:

sudo tmutil compare                      # compare computer to latest backup
sudo tmutil listbackups                  # list available backups
sudo tmutil compare <backup1> <backup2>  # compare two backups from backup list

This should give you a good idea about where the volume is coming from.



tmutil calculatedrift machine_directory

gives you an overview of the sizes differences between each consecutive backup.

It is useful to pinpoint when exactly that happens, and which backup you should compare with:

sudo tmutil compare <backup1> <backup2>

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