Re-linking to old Time Machine backups

[Myles Davis]

I've been trying to find a solution for this fairly common problem but can't find anything that addresses it specifically for Yosemite, and the solutions for Lion/Mountain Lion don't seem to work, so I thought I'd start a new thread here.

Problem:

I changed the disk selected in Time Machine preferences. My old USB external drive that I've used for backups for a couple of years was disconnected.

The idea I had for a different drive for TM backups didn't work out. Now, I want to go back to using the old USB external backup drive.

I can enter Time Machine and see all my backups. However, the Restore button won't work, even when I click on a file.

All my backups are visible in Finder, with the folder hierarchy of Backups.backupsdb/MMS[my computer name]/dated backup folders.

When I select the old USB backup drive in TM preferences, it mounts, but I get the status of "Oldest backup: None/Latest backup: None".

I think that covers it, but if I've missed anything, please let me know.

When I was trying to make the alternate backup work (a pseudo-NAS of a drive mounted to a Netgear router) I changed the TM drive using sudo commands. I'm hoping that there is a simple Terminal command that will get me back up and running on my old USB backup with access to my old backups. I'm also hoping I didn't screw anything up permanently.

Many thanks for any suggestions.

Myles

 

[Myles Davis]

Well, my problem didn't exist and I didn't know it. Because of the "Oldest backup: None/Latest Backup: None" status in TM preferences, I had not turned TM on for fear of erasing the old backups. In checking on the TM preferences, though, I left TM on accidentally, and it's begun backing up - and it's doing an incremental backup, and all the old backups are there.

So maybe this will be helpful to someone in a similar situation.