ZFS with multiple boot/root pools

[Peter Jeremy]

On 2012-Apr-30 17:14:30 -0500, Bryan Drewery <bryan at shatow.net> wrote:
>On 04/30/2012 04:07 PM, Peter Jeremy wrote:
>> I have boot/root on one ZFS pool and for recovery purposes keep a 
>> second ZFS boot/root pool in case the first one becomes
>> unbootable.
...
>'zfs set canmount=noauto' on all of your non-active datasets. This
>will stop 'zfs mount -a' (/etc/rc.d/zfs) from mounting them.

That's OK for preventing filesystems on the secondary boot pool from
auto-mounting when booting from the primary pool but doesn't handle
booting from the secondary pool - a "zfs mount -a" there will
automount all the primary filesystems instead of the wanted secondary
ones.  That said, this does appear to be the closest to a usable
workaround at this time.

>There's also a port sysutils/beadm for managing multiple boot
>environments.

I've noted that there's work being done on boot environments.  Whilst
this is welcome, it is orthogonal to having multiple boot pools.  In
particular, boot environments don't handle the situation where
[gpt]zfsboot refuses to load the kernel.  Whilst there have been some
improvements to the ZFS bootloader, it is still unable to handle all
ZFS fragmentation results - in which case you need an alternative
boot pool.

-- 
Peter Jeremy
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