I have an external 500 GB HDD that I've used for Time Machine backups for three different computers:
- An old PowerBook G4
- A white MacBook
- My current retina MacBook Pro
I now have less than 100 GB free on the backup drive, so sooner or later it's going to fill up. I know that when the disk fills up, Time Machine will start deleting the oldest backups in order to make room for the new ones.
My question is: will it delete the oldest backups only for the machine that it's currently used with (which is the retina MBP), or will it delete the PowerBook's backups since those are technically the oldest on the disk, even though they're from a different machine?