Home Forums FineTunedMac Community Lounge First Look At Big Sur

joemike: I finally got around to testing installing Big Sur on a drive with a Carbon Copy Cloner created data volume clone. Piece-of-cake 🍰. I cloned my data volume to an external drive using CCC then booted the Recovery Drive and installed Big Sur on the external volume. When the external drive booted after the install it came right up, even my just rearranged LaunchPad settings were just as they had been. The only way I could immediately tell the difference was the CCC warning about suspended tasks that popped up. Admittedly it took a lot less time than yesterday's recovery from Time Machine.

artie: How about reversing that procedure and cloning your data volume to an external drive that's already got macOS installed on it?

joemike: An interesting idea, but sadly one that does not work. I just tried re-cloning the data volume on my bootable Big Sur clone. The cloning process was very quick, but when I attempted to boot the re-cloned drive i kept getting a reversed ⌀ symbol and finally had to quit the process with the power switch."

First, thanks for asking about this. Nobody mentioned this problem at all, but I was concerned enough that I did some additional testing. I did find a problem in which CCC was rendering a previously-bootable volume non-bootable. The problem occurs if you were to install Beta 9, for example, onto a backup disk, and then clone a Beta 10 source to that backup. CCC doesn't copy the System, but it does update the Preboot volume. That's where things were going awry – there are kernel caches in the Preboot volume that shouldn't be copied because the beta 10 kernel caches can't boot the beta 9 system. Anyway, I fixed that for the general 5.1.22 release, so I'd want to see if this other person can reproduce that problem with the latest build of CCC.