Questions about Debian initrd documentation

[Yvan-Masson]

Hi,

Thanks for documenting OpenZFS. I am experimenting on a fresh Bullseye VM with root on ZFS, following the current PR #205. Grub is installed in BIOS mode and there is only one disk. System works properly, but the current Debian initrd documentation does not match what I have:

1. The Grub linux command line in the "Booting from snapshot" section is different. If we remove the snapshot mentioned to have the original line, the doc gives :

linux   /ROOT/debian-1@/boot/vmlinuz-3.2.0-4-amd64 root=ZFS=rpool/ROOT/debian-1 ro boot=zfs $bootfs quiet

While on my system it is:

linux   /BOOT/debian@/vmlinuz-5.10.0-9-amd64 root=ZFS=/ROOT/debian ro root=ZFS=rpool/ROOT/debian quiet

Maybe it is just Grub that is much newer in Bullseye than in the documentation?

2. The doc says it should be possible to select snapshot dynamically by adding @ only to the root parameter. In my case, system just hangs after Loading initial ramdisk ...

3. I tried a rollback from snapshot by specifying the snapshot name in the root parameter and by adding rollback=1. System then hangs (see picture below). After enforcing a reset, system boot properly on the previously selected snapshot. Maybe this could be better explained in the documentation?
   

Regards,
Yvan

[gratuxri]

Can you do cat /proc/cmdline in busybox screen and post it here?

[Yvan-Masson]

Of course: BOOT_IMAGE=/BOOT/debian@/vmlinuz-5.10.0-9-amd64 root=ZFS=/ROOT/debian ro root=ZFS=rpool/ROOT/debian@2021-10-13_14-06 rollback=1 quiet

I also tried adding the @snapshot to the two root parameter, but result is identical.

[rlaager]

The Root on ZFS HOWTOs use a separate bpool and have for a while now. I didn't write those other docs. I've made some minor tweaks to bring it closer.