Resolved Time machine with different OS versions

[insonias]

Hello,

I updated my macbook pro from El Capitan to Mojave a few months ago. While using the El Capitan I used an external hard drive to make backups using Time Machine and I want to use it again. My question is: can I select the same drive to make the Mojave backups? Will I still be able to access the files on the El Capitan backups?

Thanks in advance!

 

[KALLT]

If the backup was created for the same macOS installation (albeit El Capitan instead of Mojave), then yes. Time Machine can “inherit” previous backups and build upon them. Just keep in mind that the first backup between OS versions is multiple GBs big. If you are running out of space and have Time Machine set to delete older backups automatically, you might lose the El Capitan backups.

 

[insonias]

Thanks Kallt for your answer. I just called the support line and even though I have a lot of space on the disk, I'll use another one to make the Mojave backups.

 

[KALLT]

You could also just partition the hard drive and use the new partition for new backups. You could even remove all but one El Capitan snapshot to keep the size of the other partition as small as possible.

 

[Soba]

Thanks Kallt for your answer. I just called the support line and even though I have a lot of space on the disk, I'll use another one to make the Mojave backups.

Just to be clear on the point, and while there’s nothing wrong with using a new disk, it is 100% supported and okay to use an existing backup disk from the same Mac. Your backup history will be fully maintained and accessible if you do so.

You can even use the same disk on a different Mac, though it will start a separate backup history in that case.

I’m curious if the Support technician said something that scared you away from using the same disk?