Big Sur 11.2 SoftRaid 6.0.1.b48
My Thunderbay 8 has some JBODs, one of which is devoted to Time Machine. Having just upgraded to big Sur I decided to erase the disk and start a new TM backup for Big Sur. The erase works fine, the problem occurs when I try to add it in Time Machine Preferences. Preferences says it is preparing the disk (HFS+ formatted) but the progress bar freezes at about 50%. The Disk has at this point been ejected. System Preferences at this point is hung and I have to kill it. I remount it and try it again. Again TM disk preparation freezes at 50% and the disk is ejected.
The problem is with Big Sur, Time Machine (at least on SoftRAID volumes) requires it to be in APFS format, or it hangs the process.
We do not have the ability to "convert" an HFS volume to a SoftRAID APFS volume.