Time Machine problem

Avatar Michael Corgan
About once a month I back up my iMac hard drive to an external drive that I keep at a neighbours (not that I am paranoid). To do this I swap the external drive with my Time Machine hard drive - because they are the only two of my external hard drives which are USB3. And naturally I reconnect the Time Machine when the backup is completed.
This has always worked satisfactorily - until this week. Now I have found that Time Machine has only backed up on the two days since the reconnection. But is now telling me that there is insufficient room to backup while not offering to delete any files. Looking at the contents of the disk I can see back-up folders in the Backups.backupdb folder going back to February 2017, but TM is not seeing them! As I have all the info securely backed up anyway, I am happy to re-format the TM drive, but would prefer to re-access the back-up folders.
So,two questions:
Can I get access to the backups?
And, did this happen because of disconnecting the TM drive?

Re: Time Machine problem

Avatar Mick Burrell
If the Mac detects a drive that is not its current TM drive, it asks if you want to use it (from memory) as well as the existing or instead of the existing. It sounds as if you may have chosen the latter and the TM app is now looking to do its backups on the drive you store with your neighbour and seeing your existing TM drive as a new one. If that's the case, I'm sure there will be a way to revert to seeing the old data.