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I am slowly migrating from an older Mac Pro to a MacBook Air. Both machines are backed up to two different 2TB drives using Time Machine. Recently I decided that I wanted to make the extensive data I have on my older Mac Pro more available to my MacBook Air, so I bought a 1TB portable drive which I can keep with me.

I moved approx. 430GB of data onto the portable drive ('SideCarlson'). This was enough data that I figured trying to back it up while associated with the Air would not work (I read somewhere that if TM is backing up two different computers, it can't delete old backups of the OTHER computer to make room for the current one)

So, I backed it up while associated to the Mac Pro.

Question: Can I drag this backup to the new machine's backup? (See screenshot)enter image description here

I'm assuming I would need to:

  1. Make sure both machines' backups are current (I see both have a backup in progress)
  2. Turn off Time Machine in Mac Pro ('jPro')
  3. Restore 'SideCarlson' from the MacBook Air ('Air Carlson')

Thanks for your help :)

2 Answers 2

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No, you can't do this. The folder you've selected doesn't contain the entire backup, just the changes from the last backup, and many symlinks to the older data contained in other backups. Such symlinks will break if you do this.

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  • thanks! does this change at all if that's the first backup of the volume? Forgot to mention that. Jan 20, 2014 at 19:02
  • @Jeremy If it's the first backup, things are slightly different. It might work, but I'd always do a Verify Backups after such changes (⌥-click the Time Machine menu bar icon), and a backup of the backup is probably a good idea… :)
    – grg
    Jan 20, 2014 at 19:04
  • I just tried moving and was told, "The operation can’t be completed because backup items can’t be modified." I think I'm going to try a different tack. Thanks! Jan 20, 2014 at 19:23
  • @Jeremy Yeah, Finder will prevent you from modifying Time Machine backups (for good reason). You can try with Terminal though.
    – grg
    Jan 20, 2014 at 19:25
  • @grg I don't think this is correct: Those are not symlinks but hardlinks. That are files referring to the same space on disk. So if you delete one, the ref-count simply is decremented, until all refs are gone, then the file is deleted. So there is no difference between the first back and later backups. Throw away any backup and later files still exist. To answer Jeremy's question: I think the OS won't allow it. I am looking for a way around this too!
    – mous
    Jun 26, 2021 at 10:59
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It seems that modifying an existing backup won't work. What you CAN do, is move a complete backup to another machine's backup, so one level higher than your example. So look for the backup that contains the last version of the directory you want, then move the complete backup. This won't take up any extra space. Next time you do a normal backup on the machine you moved it to, it'll recognise that volume and go incremental on that one. This works.

I did the moving in the terminal after sudo -i, because in the finder this does not work.

Did this in Big Sur by the way. A bit late, this post is 7 years old, but should be helpfull for other people in the future!

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