Hello, few notes about BigSur beta 3 now the BaseSystem.dmg is 884 MB (beta 2 was 740 MB), also from single user mode they introduced two new commands to easily mount the Data and Preboot Volume (both Volumes writable from single user mode even with a sealed system snapshot booting):
mount -P 1
mount -P 2
mount -vat nonfs
thanks to the
@ASentientBot "apfs_systemsnapshot method", I have disabled on BigSur beta 3 snapshot booting directly from BigSur (without its Recovery), here are the steps, the two requirements are from a macOS Recovery or terminal recovery:
nvram boot-args="-no_compat_check"
csrutil disable
then from BigSur normal booting, open terminal and follow these steps:
Code:
sudo mkdir ~/Snapshot/
(this makes an empty folder mount point on your home folder so copy exactly as written)
mount
(on the first output line you can notice a diskXsYsZ you have to consider only diskXsY)
sudo mount -o nobrowse -t apfs /dev/diskXsY ~/Snapshot/
tmutil listlocalsnapshots ~/Snapshot/
(this show eventually the snapshots in form of "com.apple-UUID" rather than date time)
sudo mount -uw ~/Snapshot
(this makes writable the mount point)
cd /S*/L*/File*/apfs*/C*/R*/
sudo ./apfs_systemsnapshot -v ~/Snapshot -r ""
(credit to ASentientBot for the apfs_systemsnapshot that tags an empty string to disable snapshot)
if for some reason using this posix path ~/Snapshot won't allow to tag the snapshot, then use instead /Users/yourusername/Snapshot
if after those commands you get this message:
Attempting tagging of snapshot on volume: /Users/yourusername/Snapshot
then after reboot you can use "sudo mount -uw /" .
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