use Time Machine disk again after removing from backup list

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Level 2

152 points

use Time Machine disk again after removing from backup list

If you remove a disk from Time Machine's list of disks to back up, and then add it as a backup disk again much later (but still using the same computer), will it recognize the previous backups and pick up where it left off, or will it start a new set of backups?

In other words, once a disk is removed from Time Machine Preferences, then if it's added back later, will it automatically see the existing backups as belonging to the same computer?

Thank you.

Posted on Apr 17, 2014 6:51 AM

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Answer 1

ssls6

Level 4

2,879 points

Apr 17, 2014 7:32 AM in response to DonnaR

Do you mean...

Disks 1, 2, 3 backed up to Disk A & B......B was removed but added back?

Or do you mean....

Disks 1, 2, 3 backed up to Disk A......3 was removed and then added back?

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Answer 2

DonnaR Author

Level 2

152 points

Apr 17, 2014 8:16 AM in response to ssls6

I mean Computer 1 backed up to (external) Disks A & B.... Disk B was removed and then added back. Sorry if I wasn't clear before.

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Answer 3

ssls6

Level 4

2,879 points

Apr 17, 2014 9:52 AM in response to DonnaR

I thought that is what you meant but I just wanted to be clear myself. If you add B back, in my experience should work as you expect with the exception that many files will be updated the first time. I have also experienced problems where the first backup to an added disk hangs causing me to reformat the drive and doing a full backup on it.

Two drives with Time Machine result in "ping-pong" or alternating complete copies of your files. If you are using time machine as an archive (very dangerous) for files you don't want on your main computer but want to save, please consider some alternative.

Finally, there are command line utilities to inherit an older backup if your computer doesn't want to pick up where it left off on Drive B. Taking a few moment's to read some of Pondini's work can be a life saver when you run into time machine problems and don't want to just make a new backup.

http://pondini.org/OSX/Home.html

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Answer 4

DonnaR Author

Level 2

152 points

Apr 17, 2014 10:09 AM in response to ssls6

Thank you! Yes, I've read Pondini's work extensively, thought he was wonderful, and was very sad to hear that he'd passed away.

Re your response: I only use TM disks as backups (not as archives).

So to clarify: in your experience, when you've added "Disk B" back (previously used to back up that same computer), you've experienced both things -- that Time Machine picked up where it left off, and where it didn't work and you had to erase and start over...?

Thanks again.

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