When planning migration from an older to a newer Mac drive while using the same Time Machine, I often see mentions associatedisk and inheritbackup verbs of tmutil--but fail to find any clear definition of how they are different.

What are differences between inheritbackup and associatedisk? How one chooses between them (or chooses both) in their specific situation?

  • Can you pls clarify what you mean by "a newer Mac drive" and "the same Time Machine"? Do you mean starting to use a new external drive for TM backups of the same computer or using your existing external drive for TM backups for the TM backups of a new computer after migrating all your files and other data from the old computer to the new one or what?
    – Alper
    Commented Sep 14, 2023 at 20:56

1 Answer 1


You mean: What are differences between inheritbackup and associatedisk?

  • associatedisk connects a new device to make backups on your old TMBackup, e.g:
sudo tmutil associatedisk -a /Volumes/MACINTOSH_HD/ /Volumes/TIME_MACHINE_VOLUME/Backups.backupdb/COMPUTER_NAME/Latest/HD_NAME/
  • inheritbackup tells TM to inherit all your old TMBackups with the new device. Means when you start Time Machine.app you can see all your backups far to the oldest one, e.g:
sudo tmutil inheritbackup /Volumes/TIME_MACHINE_VOLUME/Backups.backupdb/COMPUTER_NAME/
  • 1
    Here, device is a Mac, right? And I'm still struggling to understand difference between them.
    – yurkennis
    Commented Sep 11, 2023 at 13:29
  • Device can be HD, SSD, SD, MacHardware a.m. Simple say: associatedisk tells the Mac to make Backups to the new specified HD. inheritbackup tells the mac to recognise all the old backups made before you changed the Hardware. Mac or HD.
    – Atalantia
    Commented Sep 15, 2023 at 7:01

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