ZFS boot on zfs mirror

[George Hartzell]

Dmitry Morozovsky writes:
 > On Tue, 26 May 2009, Mickael MAILLOT wrote:
 > 
 > MM> Hi,
 > MM> 
 > MM> i prefere use zfsboot boot sector, an example is better than a long talk:
 > MM> 
 > MM> $ zpool create tank mirror ad4 ad6
 > MM> $ zpool export tank
 > MM> $ dd if=/boot/zfsboot of=/dev/ad4 bs=512 count=1
 > MM> $ dd if=/boot/zfsboot of=/dev/ad6 bs=512 count=1
 > MM> $ dd if=/boot/zfsboot of=/dev/ad4 bs=512 skeep=1  seek=1024
 > MM> $ dd if=/boot/zfsboot of=/dev/ad6 bs=512 skeep=1  seek=1024
 > 
 > s/skeep/skip/ ? ;-)

What is the reason for copying zfsboot one bit at a time, as opposed
to 

  dd if=/boot/zfsboot of=/dev/ad4 bs=512 count=2

g.