10.5: Remove obsolete disks from Time Machine

Oct 26, '09 07:30:05AM

Contributed by: Anonymous

Leopard only hintBy now, everyone knows how to delete a file or folder from time-machine using the Gear menu in Time Machine's Finder view. But I was puzzled by the problem of deleting entries for an entire external disk I no longer had. Because that disk was no longer available, I could not simply attach the disk and then use Time Machine to delete the backups for it. You also can't do this with the Finder (it won't let you edit the Time Machine folder). And you probably would prefer not to do it by hand in Terminal, since there might be Time Machine database entries this would gum up.

The solution is to navigate in the Time Machine interface not to the disk itself, but to the backup entry for that disk on the Time Machine disk itself. Specifically, in Time Machine's Finder view, select the Time Machine disk, then enter the Backups.backupdb folder, and drill down to find the last entry for the obsolete disk. Then tell Time Machine to delete all backups of that entry. The original disk need not be connected!

If you think about this, it's an unexpected behavior since it's outside the standard paradigm of pointing to the "real file" you want to remove the backups of.

This is handy because Time Machine promiscuously tries to back up even temporarily-connected drives which might not be your own, leaving you with orphan backup entries you don't want. This has only been tested on 10.5, but probably works the same way in 10.6.

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