Re: ZFS on Debian GNU/kFreeBSD

[Robert Millan]

2010/7/22 Seth Goldberg <address@hidden>
>> I guess the API exported by libzfs can serve for this?  But first, I
>> have some concern about zfs.mod, I'll write a detailed mail about that
>> later.
>
>  That's how I'm implementing it, though libzfs is technically an uncommitted 
> interface.

What are you currently implementing? I just want to make sure I don't
duplicate existing work.

>> Uhm this sounds wrong, grub-setup isn't meant to handle filesystems
>> (it does something like you describe for RAID1, but only because it
>> can rely on the storage backend being 1:1).
>
>  [...] To be truly fault-tolerant, if we're booting from a zfs pool, there 
> must be an embedded config file that searches for a (non-faulted) root device 
> from the pool's mirrors as well.  Separate invocations for each device in the 
> root pool mirror are fine, though.

Ah, I understand you now. You want to take advantage of ZFS' fault-tollerancy
for boot blocks. I'm not sure this would make sense, because we have to give
up at some point (e.g. boot.img can't benefit from this), so we're just moving
the line. In any case, I just want the basic functionality to work and it's not
currently in my plan to implement this (sorry ;-)).

>  BTW, I've run into a similar issue (comparing major/minors) in updating 
> grub-probe to deal with zfs -- grub_make_system_path_relative_to_its_root() 
> compares st_dev with the st_dev's of each path component.  This won't work on 
> ZFS either because GRUB files are stored in the top-level filesystem and 
> because the root filesystem (for the purposes of GRUB2's $root) is a 
> different filesystem than the top-level filesystem.  GRUB2 was never designed 
> to deal with this kind of disparity (even at the RAID level).

Can you map st_dev to zpool name (and later to zpool devices) using libzfs?