Originally Posted by artie505
Thanks for the volume structure info, but it's mostly over my head, but...
Originally Posted by joemike
APFS Container “AppleAPFSMedia”
Physical Disk “RecoveryOSContainer”
APFS Volume “Update”
APFS Volume “Recovery” (and its equivalent Intel Mac structure) is the fallback recovery (essentially the previous macOS version) (Emphasis added)
suggests that there's a full macOS installation in Recovery, which I've always thought hasn't been the case.
What is new to me and to Big Sur is the Fallback Recovery Drive which is the Recovery Drive from the previously installed version of MacOS. This Eclectic Light Company article does a good job of explaining the three Recovery modes on M1 Macs (This article covers all of the M1 startup modes). What is missing on M1 Macs is the Internet Recovery Drive (⌘⌥R), which is why I keep a bootable thumb drive installer with the current release version of macOS on hand.

If you look at the volume structure of Big Sur on an Intel Mac
Originally Posted by Intel Mac Volume Structure
APFS Container “AppleAPFSMedia”
Physical Disk “Customer”
APFS Volume Group “Macintosh HD”
APFS Volume “Macintosh HD”
APFSSnapshot“com.apple.os.update-...
APFS Volume “Macintosh HD - Data”
APFS Volume “VM”
APFS Volume “Update”
APFS Volume “Preboot”
APFS Volume “Recovery” Physical Disk “Macintosh_HD2”
APFS Volume Group “Macintosh HD”
APFS Volume “Macintosh HD”
APFSSnapshot“com.apple.os.update-...
APFS Volume “Macintosh HD - Data”
APFS Volume “VM”
APFS Volume “Update”
APFS Volume “Preboot”
APFS Volume “Recovery”
What is missing is the iBoot System Container and its contents. The equivalent functionality on Intel Macs is apparently in firmware or at least is not in an APFS volume format. If you think of it that makes sense as the Intel system predates APFS. Unfortunately TinkerTool System does not indicate the permission status of the various APFS structures so the iBoot System Container could be on the NVME, in firmware, or even in hardware. Thanks loads Artie, this has given me more research to do. (Why isn't there an emoji for sarcasm when you need one? 😜)

By-the-way This Apple Article explains how you might get in a situation where using the Recovery Drives is not an option and how to use a second Mac to recover the Recovery drive.


"All you've got to do is own up to your ignorance
honestly, and you'll find people who are eager to
fill your head with information"
--Walt Disney