Time Machine wants to erase my backup drive

[kenfused]

When using Time Machine (after upgrading to Big Sur, not sure that is related) on my external HD, time machine said it was full. So I deleted the old backups (I have a 2nd HD also) and was ready to start a new backup fresh.

I also keep a few archived files on that disk.

When I try to select the Drive for a new backup, Time machine wants me to Erase everything( Which I dont want to do now) on the disk to start using it as a new Time Machine backup. It says "The volume must be erased because it contains existing data"

Does Time Machine no longer allow any non- time machine data on a particular HD to use it for TM?

 

[gilby101]

With a direct attached (USB) disk, Big Sur TM wants to backup to a newly formatted APFS volume which will be used just for TM. By default that will erase the whole disk.

I had an external disk with both Catalina TM and other filers. What I did: Copy the other files elsewhere. Erase the whole disk in Disk Utility with an APFS volume with a suitable name. Configure TM to use that volume - it will reformat it anyway. After TM completes the first backup, add an additional APFS volume inside the APFS container (along side the TM volume). Copy the 'other files' into that volume.

Risk with all that is that you have a disaster before the first new backup completes. Really good if you can use a new/different disk for BS TM, keeping your old Catalina TM somewhere safe.

 

[FreakinEurekan]

Sounds like it got erased improperly to use as a new Time Machine drive. Move the files to a different disk, then let Time Machine erase it so that it's set up properly.

 

[Honza1]

Disks are cheap, nearly free compared to few years ago. Buy new one, keep the old one as backup. You can always read the data from teh old TM disk, if necessary manually...

 

[kenfused]

Thanks. Will get a backup drive and move files around.