booting off a ZFS pool consisting of multiple striped mirror vdevs

[Matt Reimer]

On Tue, Feb 16, 2010 at 12:38 AM, Dan Naumov <dan.naumov at gmail.com> 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 :)
>

Booting from a stripe of two raidz vdevs works:

FreeBSD/i386 boot
Default: doom:/boot/zfsloader
boot: status
pool: doom
config:

                    NAME      STATE
                    doom     ONLINE
                  raidz1     ONLINE
            label/doom-0     ONLINE
            label/doom-1     ONLINE
            label/doom-2     ONLINE
                  raidz1     ONLINE
            label/doom-3     ONLINE
            label/doom-4     ONLINE
            label/doom-5     ONLINE

I'd guess a stripe of mirrors would work fine too. If I get a chance I'll
test that combo.


> 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 doesn't work or is that "everywhere" also out of date after your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? :)


It's probably unsupported in Solaris/OpenSolaris because of their
bootloader. Our bootloader is completely different from theirs and so is not
subject to those restrictions in the ZFS docs.

The bottom line is that I think FreeBSD can boot from pretty much any
configuration, except possibly from systems with huge numbers of disks.

Matt