How does Time Machine handle a full disk?

[ger19]

I’ve been using Time Machine (TM) for about a year now and the drive I have to store the data is just over half full. I’m wondering how TM will handle a full (filling up) disk and if I need to do anything in the near future. I recall reading that you shouldn’t let the data disk that TM uses to go past 50% full. Not sure if that’s true, but that’s why I’m asking about it. What will happen as the disk gets full? Will it, at some point, just start erasing the oldest backup? Is there any magic to keeping the disk less than full? Should I start deleting from the oldest backups forward to keep the disk under a certain percentage full?

 

[Bigwaff]

What will happen as the disk gets full? Will it, at some point, just start erasing the oldest backup?

Yup.

 

[hg.wells]

Time Machine will erase the oldest backup first. Because they are full and incremental backups it’s best to let Time Machine manage the process automatically.