Errors booting of the ZFS alternative mirror disk

[Willem Jan Withagen]

Hi,

I've configured a fresh and new Supermicro server (with an X8SIL-F 
motherboard) an 2* 500GB seagate  ST3500514NS 's.
Disks are connected to:
	atapci0: <Intel 5 Series/3400 Series PCH SATA300 controller>

I've created gpt partitions for freebsd-boot,swap,zfs on both disks.
Wrote gptzfsboot in boot bootsectors.
gpart add -s 128 -b34 -t freebsd-root ad{4,6}
gpart add -s 16G      -t freebsd-swap ad{4,6}
gpart add -s 100G     -t freebsd-zfs  ad{4,6}
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ad)4,6}

After which I did the "regular stuff" to create the system.

Which seemed to have worked because when both disks are in the system 
everything is hunky-dory and boots as expected.
Same for booting with the second disk removed.

But with only the second disk in the system, it does not boot. Not even 
when I put it in the bay of the first disk.

On screen I get:
Error 1  lba 32
Error 1  lba 1
Error 1  lba 32
Error 1  lba 1
No ZFS pools located, can't boot

I browsed thru the ZFS bootcode, but that is way to sophisticated for me.

So why doesn't it like to boot of the second disk?
What did I forget to do?

Which is what I would like for this system to be able to do, in case of 
failure of the first disk.

Thanx,
--WjW