booting off a ZFS pool consisting of multiple striped mirror vdevs

[Robert Noland]

On Tue, 2010-02-16 at 10:38 +0200, Dan Naumov wrote:
> > I don't know, but I plan to test that scenario in a few days.
> >
> > Matt
> 
> Please share the results when you're done, I am really curious :)
> 
> 
> > It *should* work... I made changes a while back that allow for multiple
> > vdevs to attach to the root.  In this case you should have 3 mirror
> > vdevs attached to the root, so as long as the BIOS can enumerate all of
> > the drives, we should find all of the vdevs and build the tree
> > correctly.  It should be simple enough to test in qemu, except that the
> > BIOS in qemu is a little broken and might not id all of the drives.
> >
> > robert.
> 
> If booting of a stripe of 3 mirrors should work assuming no BIOS bugs,
> can you explain why is booting off simple stripes (of any number of
> disks) currently unsupported? I haven't tested that myself, but
> everywhere I look seems to indicate that booting off a simple stripe
> doesn't work or is that "everywhere" also out of date after your
> changes? :)

I would need to setup a qemu test for it... But I can't think of a
reason that it shouldn't work.  I currently boot from two physical
drives attached to the root.  In the boot code we enumerate all the
physical vdevs, so that we can correctly identify the correct disk and
offset from the block pointer.  The mirror driver is really pretty
simple.

robert.

> 
> - Sincerely,
> Dan Naumov
-- 
Robert Noland <rnoland at FreeBSD.org>
FreeBSD