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Time Machine Back Up/External HD

Can I transfer a prior TM backup from one external HD to another external HD? Thanks.

MacBook Pro 13″, macOS 10.15

Posted on Nov 27, 2021 12:33 AM

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Question marked as Top-ranking reply

Posted on Nov 27, 2021 7:21 PM

See these instructions from Apple

https://support.apple.com/guide/mac-help/if-the-time-machine-backup-disk-is-full-mh15137/10.15/mac/10.15


Apple indicates that it is best to start with a fresh new backup on a new drive. But Apple also says that you can move the existing backup to a new drive:


If you ... wish to preserve your existing backup history, you can copy the Backups.backupdb folder from the old disk to the new one. Use Finder, and not Terminal or any other app, to copy the Backups.backupdb folder. (The folder is large, and it may take a long time to copy.)


Based on what others have reported, very large backups covering long timespans and many dates sometimes fail to copy because of the complexity of the file/folder structures being copied and because it takes so long for the copy to complete. There are also sometimes problems with user permissions (you may not have permission to access Time Machine backup folders for other users) that cause the transfer to fail.


Many recommend instead simply starting a fresh new Time Machine backup series with a new backup drive and keep the old one in case older backups need to be accessed form the past.

2 replies
Question marked as Top-ranking reply

Nov 27, 2021 7:21 PM in response to spikejj

See these instructions from Apple

https://support.apple.com/guide/mac-help/if-the-time-machine-backup-disk-is-full-mh15137/10.15/mac/10.15


Apple indicates that it is best to start with a fresh new backup on a new drive. But Apple also says that you can move the existing backup to a new drive:


If you ... wish to preserve your existing backup history, you can copy the Backups.backupdb folder from the old disk to the new one. Use Finder, and not Terminal or any other app, to copy the Backups.backupdb folder. (The folder is large, and it may take a long time to copy.)


Based on what others have reported, very large backups covering long timespans and many dates sometimes fail to copy because of the complexity of the file/folder structures being copied and because it takes so long for the copy to complete. There are also sometimes problems with user permissions (you may not have permission to access Time Machine backup folders for other users) that cause the transfer to fail.


Many recommend instead simply starting a fresh new Time Machine backup series with a new backup drive and keep the old one in case older backups need to be accessed form the past.

Time Machine Back Up/External HD

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