MacOS – Unable to Access Local Snapshots when external Time Machine is disconnected


My local snapshots are behaving weirdly. When no Time Machine backup is connected and if I enter time machine, I get this prompt:

Your Time Machine backup disk can’t be found.

…but when my external Time Machine is connected, I can browse through both pink and white (local) coloured snapshots.

Another observation is if I go to /Volumes I can see the MobileBackups volume. When a Finder window of /Volumes is open and I enter Time Machine I am able to browse local snapshots even when my external time machine drive is disconnected.

Any help regarding this issue would be appreciated 🙂

Best Answer

I have seen this on several occasions and I have done this to clear up the corruption or glitch that prevents browsing local snapshots without an actual full time machine destination mounted:

  1. Connect to one of my destinations and force a good backup

    tmutil startbackup --block --rotation
  2. Disable local snapshots

    sudo tmutil disablelocal
  3. Enable local snapshots - being sure the cleanup is done

    sudo tmutil enablelocal

I do watch the console app (or tail -f /var/log/system.log) during the backup and commands above to make sure that the local filesystem gets cleaned up and give the computer several minutes between the disable and the re-enable since it does have to unmount the network filesystem, delete old copies of files and clean up things before trying again with a local snapshot.

The downside of this is you do lose any copies of files that only existed on the local snapshot intervals and didn't get saved to an actual remote location. It also doesn't really dig into why the store became corrupt so you might have the same thing happen again at a later date. I've also had good luck with reproducible time machine problems reporting it to Apple for assistance. They'll want you to run tmdiagnose and probably not reset things like I mentioned above if you want to get at the root cause of what really happened as opposed to getting it working again.