Do not install Big Sur on the same APFS container as previous versions of MacOS
So it looks like it would be a bad idea to install macOS Big Sur on the same APFS volume as your existing macOS system:
Well that’s a big OOPS!
Oh, yikes! Thanks for the heads-up @brianmonroe!
Hopefully that's remedied in a future beta.
@davehamilton I am not sure it will be. This is why I am with @johnfbrawn on this one. If you do not want to do an in place upgrade of your main boot volume, just install it on to an external drive. This way it is much cleaner and will work. From what I have seen over the decades I have worked with computers, trying to have more than one OS on one drive can be a challenge in the best of times and now with the ability to run multiple OS's in VM's, having them hosted or just getting another drive as drives are cheep now it really does not make much sense to do so.