Re: Problematic upgrade from 7.2 to 8.0 with ZFS file system

>
> I honestly don't know how the right way to solve the problem, but here are
> some ideas:
>
> * the kernel ABI *should* be compatible with userland tools at least one
> major version backward. I understand that this might now be impossible, but
> it is possible to bring back enough of the old ABI to allow for zfs to
> mount?

No. There are many issues that have much higher priority.

>
> * freebsd-update could automatically detect this situation and install the
> new zfs userland at the same time as the new kernel

Need to talk to the update maintainer.

> * lots of of clear documentation about what course of action a user should
> follow if they are performing a source update. Should the recommendation be
> changed to install userland *before* rebooting, and then immediately reboot
> before some of that userland explodes against the old kernel in memory?

UPDATING explicitly states that the two need to be in sync or the user
tools will not work.

> The existing recommendation is based on the fact that the new kernel will
> continue to work after reboot with the old userland.

> If that assumption is
> not always true then the whole FreeBSD installation process needs
> rethinking.

I don't think so. It is well understood that ZFS is an external code
base, and like any third party application, users need to to inform
themselves when updating. Just because it works fairly well, I don't
think we should mislead ourselves in to believing that all the rough
edges can be removed in the near future.

-Kip