So this may be a misunderstanding as I am still getting to know my MacBook Pro, But can the majority of an internal drive be occupied by Time Machine backups?

I was looking at the space taken up on my 250 GB drive, and noticed it was down to 43 GB free. I was perplexed to say the least. So after a bit of digging I went into About this Mac -> Storage, and discovered 180 GB taken up by backup. I was even more confused because I use time machine on an external drive. I am not certain of the logic, I have tried to solve this myself but I no idea as to how to remove this dumb backup on the mac's HD. Maybe I am the dumb one, anyways could someone please explain to me how to fix it.


Since OS X 10.7 (Lion), Time Machine (if enabled) keeps local snapshots on portable Macs. This gives you Time Machine-like access to recent backups, in case you need to restore a deleted or modified file (however you still need a proper external backup to protect against disk failure). This is what the Backups item is measuring.

This feature isn't enabled by default on desktop Macs (are you sure you have a Mac Pro, and not a MacBook Pro? One is a laptop, the other is a desktop), but can be enabled by running sudo tmutil enablelocal in Terminal, and disabled by running sudo tmutil disablelocal (you will be prompted for your password in both cases).

As noted in Apple's KB article on the subject, once free space on your disk falls below 20%, it will start trimming older local snapshots, and it will speed up this process if it falls below 10%. So if you do nothing, you should see your drive space return to approximately 50 GB free. You can continue to store new things on your hard drive without fear of running low on space, as Time Machine will just slowly trim away snapshots as you add new data.

  • 1
    Another thing to note: "The Finder displays the available space on the disk without accounting for the local snapshots, because local snapshots will surrender their disk space if needed." If there's 43GB empty and 180GB of backups, About This Mac and other places show 43GB while Finder will show 223GB free because that's what you can actually use.
    – gabedwrds
    Sep 26 '12 at 0:14
  • Rob,I took your advise and disabled it. Thanks for the explanation. I was on the phone with Apple and they did not even mention than concept. And no where in time machine does it indicate such a thing. Something else was going on too. The SSD was showing 256 gb free, on a 250 gb drive. lol. The apple tech, got me to reindex the drive. It is very late and my brain is full of C++ right now. I will look at this again tomorrow, now that the indexing sorted out the actual free space. I still want to delete any local backups, as I have the external for that. thanks
    – diek
    Sep 27 '12 at 3:25
  • gabesubdo, I appec your help too, but regardless of the concept of surrendering I do not want any local backup. thanks.
    – diek
    Sep 27 '12 at 3:27

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