2 Volume Disk one with Big Sur and one with Mojave shows incompatible disk with Mojave

Hi,

I installed Big Sur, created two volumes and then installed os Mojave on one volume, since I want to use older applications. It is all working fine except, when I launch Mojave a disk is showing up, which I guess is a disk created by Big Sur. It does not interfere with any operation except, that when I use Time Machine it is also backed up, and I am not sure to exclude it. Thanks for any explanations.

Mac mini, macOS 11.0

Posted on Nov 23, 2020 10:06 AM

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2 replies

Barney-15E

Level 10

122,048 points

Nov 23, 2020 8:13 PM in response to Cancerinform

What volume is it?

Big Sur adds an Updates volume and you can exclude that from your Mojave backup.

It also might add one that looks like com.apple.os.update....

You can exclude that one from your Mojave backup, too. It's a snapshot and seems to be how Big Sur mounts the OS volume.

Cancerinform Author

Level 1

26 points

Nov 23, 2020 8:44 PM in response to Barney-15E

Thanks for your answer. It is a volume called Update. I thought so that most probably I can exclude it from the time machine. But I wanted confirmation and got it. Thanks again.

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2 Volume Disk one with Big Sur and one with Mojave shows incompatible disk with Mojave