search

openzfs / openzfs-docs

OpenZFS Documentation
https://openzfs.github.io/openzfs-docs/
135 stars 194 forks source link

Root on ZFS: use compat=legacy with boot pool #466

Closed ghost closed 1 year ago

ghost commented 1 year ago

As mentioned here, compat=legacy seems to fix the problem where, once a snapshot of the root level dataset of the boot pool is taken, boot pool will become irreversibly unreadable by GRUB.

Also added a note against using less well-tested features in general.

gmelikov commented 1 year ago

legacy is too strict, but why not, at least temporarily. We may add a note about grub bug in future, if upstream won't fix it in a year.

colmbuckley commented 1 year ago

If we genuinely think that one or more of the current feature list in /usr/share/zfs/compatibility.d/grub2 is not, actually compatible with GRUB2, then we should be making upstream PRs to fix that. The whole point of that file is to identify which features are usable with GRUB2; it is vastly preferable to fix this file than to suggest that GRUB2 only works with compatibility=legacy bpools.

Which features are causing the problem?

colmbuckley commented 1 year ago

If people are following this guide, bpool needs very few zpool features in order to remain useful, we should definitely prune compatibility.d/grub2 to only contain features we are highly confident to work.

ghost commented 1 year ago

Well, as a student of mathematics, only a proof would make me confident about anything. Since we do not have that, I will have to contend with legacy.

To be clear, there is no guarantee (proof) that legacy will work with GRUB either.

Colm @.***> writes:

If people are following this guide, bpool needs very few zpool features in order to remain useful, we should definitely prune compatibility.d/grub2 to only contain features we are highly confident to work.

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.