How to Safely Move Time Machine Backups to a New Hard Drive

Jul 7, 2013 - 10 Comments

You can switch hard drives that Time Machine backs up to easily, but to properly migrate from one Time Machine backup drive to another and preserve the existing archived backups, you’ll want to take a few additional steps to insure that your existing prior backups are safely moved over as well.

Move Time Machine backups to a new hard drive

This is an easy process, so whether you are moving backups because you got a new larger hard drive, or because an existing drive is on its last legs, you’ll be sure to have all archived backups accessible from the new Time Machine disk.

  • Be sure the new drive is formatted for Mac OS X compatibility using Disk Utility, confirming the drive format is set to “Mac OS Extended (Journaled)”
  • Open System Preferences and go to “Time Machine”, flip the switch to OFF – this is temporary, and is done so that a new backup is not being created while you are copying existing backups
  • Turn off Time Machine temporariliy

  • With both the old Time Machine drive and new drive connected to the Mac, open a Finder window for the old Time Machine backup drive, it should contain a single folder named “Backups.backupdb”
  • Open another Finder window with the new hard drive visible, then drag and drop the “Backups.backupdb” folder from the old drive to this new hard drive – this copy process may take a long time depending on the size of the backups and the speed of the drive interfaces, don’t be surprised if it takes several hours
  • Copy Time Machine Backups to a new drive

  • Now go back to System Preferences and the “Time Machine” preference panel, then click the “Select Disk” button to choose the new drive you wish to use for Time Machine backups
  • Select the new Time machine disk

  • While in Time Machine preferences, toggle the switch back to ON to enable the automated backups again
  • Turn Time Machine back ON

  • Close out of System Preferences, a new Time Machine backup may start itself, or you can initiate one on your own

That’s really all there is to it. It’s important to reemphasize that the transfer process may take a long time due to the size of the backups. Time Machine fills out the drive space provided to it, so that means a lengthy history of backups may be copied over during this process, which can easily equal 100GB or more. If you find the time to copy the files to be obtrusively long, your best bet will be to start the backup transfer sometime in the evening and let it run all night to copy.

You shouldn’t need to do this process often, but because hard drives are so cheap with plentiful storage nowadays, it can be a good idea to get a new external drive every so often and perform a data migration like this to insure your backups are kept in good shape. The fact of the matter is that all hard drives do fail, and there is nothing worse than needing a backup and having that backup drive be malfunctioning, so if you’re storing your backups on a rusty 5 year old external hard drive, it may be a good time to grab a new one.

Finally, keep in mind that you can easily share a single drive between automated Time Machine backups and personal files, so if you wind up finding a deal on a humungous 15TB drive, you don’t need to devote the entire thing to Time Machine.


Related articles:

Posted by: Paul Horowitz in Mac OS, Tips & Tricks


» Comments RSS Feed

  1. Thanks for the help. I’m just about halfway through the file migration, but the TM backups folder is already there, and it was as easy as you said. Tomorrow, I’ll check to see if the backups are accessible on the new drive.

    Very much appreciated your clear instructions.

  2. Geoff Bonnin says:

    I have the same problem. I’m trying to copy a little less than 4TB on an external 4TB USB3.0 to an 8TB external USB3.0.
    The disk read/write speeds are very slow according to Activity Monitor.
    On one attempt a message popped up saying something about insufficient cache.

  3. Dennis Clark says:

    copying time machine to new drive, gets to the amount of data to be copied says 5 seconds remaining and the keeps copying and is now way past the amount of the original ™ data??????????

  4. IKomrad says:

    My time machine storage is on a drobo. I’m resetting the partitions ( all data lost) on the drobo so that I can use their newly available 64tb partition size.

    I need a safe space for backups so that I can put them back ono the drobo after I repartition it.

    Can I copy the backup folder to my Mac’s boot drive, repartition the drobo, then copy it to the drobo’ a time machine volume?

  5. Derick says:

    This doesn’t work consistently. After hours of preparation, my actual copy failed after only about 500 MB, with the same error message described here:

    I’m going to try Disk Utility instead.

  6. Mike Pickard says:

    “Finally, keep in mind that you can easily share a single drive between automated Time Machine backups and personal files, so if you wind up finding a deal on a humungous 15TB drive, you don’t need to devote the entire thing to Time Machine.”

    But that begs the question, “Where is the backup for those personal files?” Not on that drive, certainly. Best to leave the Time Machine drive dedicated to that single purpose.

  7. Lake says:

    What about when the destination drive already has a Time Machine backup (e.g. of a different computer). In my particular situation, I want to use my Mac to copy the backup (all the snapshots) from one external hard drive (Drive A) to another (Drive B), but Drive B already has another computer’s Time Machine backup.

    None of the backups belong to the computer I’m using to do the transferring. Finder doesn’t allow me to transfer the folder named named after the computer from Drive A’s Backups.backupdb folder to Drive B’s. I tried moving Drive A’s Backups.backupdb folder into another another root level folder on Drive B (resulting in /Volumes/Drive B/some other folder/Backups.backupdb. But tmutil refuses to work with that Backups.backupdb (presumably because it’s not on the drive’s root level). (Attempting to use tmutil to delete a snapshot in a Backups.backupdb that is not at the first level of the external drive returns “Invalid deletion target (error 22)”. Attempting to use tmutil to compare it with another snapshot returns “Can’t compare a source volume descendant to a snapshot.”)

Leave a Reply


Shop on and help support OSXDaily!

Subscribe to OSXDaily

Subscribe to RSS Subscribe to Twitter Feed Follow on Facebook Subscribe to eMail Updates

Tips & Tricks


iPhone / iPad



Shop on Amazon to help support this site