Time Machine not recognizing Mac's backup database
How can I tell Time Machine "This is the backup I want to use for this machine"?
In brief:
When I try to backup my Mac Pro to its Backup.backupdb folder on the same volume it has always been using, Time Machine does not recognize the backup as belonging to that machine. The drive icon shows up as a Time Machine drive in the Finder, but when I select it as the backup drive, it shows the Oldest and Latest backups as "None". This began when I moved the .sparsebundle from another Mac that had been backing up to the same volume (separate databases, same volume, bad idea).
Background and details:
I'm have a Backup.backupdb folder on an external volume directly connected via Thunderbolt to which I've been backing up my Mac Pro with no problems. That volume was originally the Time Machine backup drive for a MacBook Air, which was concurrently maintaining a .sparsebundle file on the same volume but was completely separate. I added the Mac Pro's backup to that drive temporarily so I could shuffle things around and make discreet volumes for the different backups. This was obviously a bad move, but it worked fine—until I wanted to put each backup on its own volume.
Time Machine was keeping the MBA backup in the usual .sparsebundle. When I first chose the same volume for the the MP backup, Time Machine made a Backup.backupdb folder for it, and every time I'd start a backup, Time Machine would ask if I wanted to inherit the other backup or keep them separate, and I kept them separate. The .sparsebundle from the MBA is now on a new volume and is working as expected, but I'm getting no joy when I try to get the MP to backup (see brief, above). Here's what I've tried:
- Moving the Time Machine pref file, but that doesn't seem to be where Time Machine stores its settings because all of my exclusions, etc. were still intact.
- Copying the Backup.backupdb to another volume by following Apple's instructions for moving a local Time Machine backup. The Finder will keep copying the 250 GB folder until it fills a 1 TB volume.
- Creating an archive of the Backup.backupdb. Keka will get stuck preparing the operation. I've let it run for up to 24 hours.
- Using Disk Utility to create a disk image from the folder. This runs indefinitely with no progress.
I originally posted about it in the thread below, but the problem has changed from "Finder not copying" to How can I tell Time Machine "This is the backup I want to use for this machine"? (Finder still won't copy it, but I don't actually need it to move—just work!
https://discussions.apple.com/thread/251684759?login=true&page=1
There are two things I can think of to try:
- Now that it's by itself on that volume, Disk Utility's "Restore" might restore the volume to a .sparsebundle that Time Machine will recognize.
- Connect the volume to another Mac and mount it over a network. Time Machine stores non-local backups as a Backup.backupdb folder instead of a .sparsebundle. Maybe it will associate the backup and machine that way and then I can somehow salvage the backup. (?)
I'd really love some direction before I do any more failed experiments. I have physical disabilities that make all the recabling between 3 Macs plus accessories a big challenge on top of the downtime it takes to run one of these tests for Apple. I'm sure there's a single command or three line shell script that will resolve this. I'd love to find it!
Mac Pro