The easy fix here is to change:
GRUB_CMDLINE_LINUX="rootflags=subvol=${rootsubvol} ${GRUB_CMDLINE_LINUX}"
to:
GRUB_CMDLINE_LINUX="rootflags=subvol=${rootsubvol},degraded ${GRUB_CMDLINE_LINUX}"
in /etc/grub.d/10_linux.
Any time your root filesystem is on btrfs, attempting to boot in a degraded state is the best choice to help recovery. You can't rebuild your btrfs raid without swapping disks and running a balance.
The easy fix here is to change:
GRUB_CMDLINE_ LINUX=" rootflags= subvol= ${rootsubvol} ${GRUB_ CMDLINE_ LINUX}"
to:
GRUB_CMDLINE_ LINUX=" rootflags= subvol= ${rootsubvol} ,degraded ${GRUB_ CMDLINE_ LINUX}"
in /etc/grub. d/10_linux.
Any time your root filesystem is on btrfs, attempting to boot in a degraded state is the best choice to help recovery. You can't rebuild your btrfs raid without swapping disks and running a balance.