After months of frustration with Yosemite performance problems, I finally gave in and completely re-installed the OS fresh. I reformatted the drive and did a complete re-install, but migrated my user files and settings when prompted via Time Machine, as part of the install process.

Question: How can I get the newly-installed OS to recognize my old Time Machine backups?

When I point Time Machine to my old backup disk, it shows "Oldest backup: None". I know that there's probably some GUID on the partition that doesn't match what's on the TM backups... is there any way to get my "new" system disk back into the Time Machine backup set without losing all the backup history?

  • Did it already create a new backup? It usually asks you if you want to continue on your old backups. Maybe check your Macs name in system preferences, sharing as well – Kevin Grabher Mar 25 '15 at 14:32
  • No, it has automatic backups: off. – Caffeine Coma Mar 26 '15 at 14:45
  • try turning it on and see if it asks you to continue on previous backups (should as soon as it starts actually running the first backup) – Kevin Grabher Mar 26 '15 at 14:53
  • Well, that sort of worked. As you suspected, it was smart enough to reconnect to my old backups simply by turning it on. Unfortunately it did not also preserve my exclusions (I have many GB of excluded data), and so as soon as it was turned on, it went about making space for the normally excluded folders. So it deleted a year's worth of backups to make space, before I could manually re-add the exclusions. – Caffeine Coma Mar 28 '15 at 13:53

You must log in to answer this question.

Browse other questions tagged .