Ask Different is a question and answer site for power users of Apple hardware and software. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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?

share|improve this question
up vote 6 down vote accepted

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.

share|improve this answer


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>
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.