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From: George Hartzell <hartzell@alerce.com>
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Date: Tue, 26 May 2009 09:42:45 -0700
To: Andriy Gapon <avg@icyb.net.ua>
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Cc: FreeBSD Stable Mailing List <freebsd-stable@freebsd.org>
Subject: Re: ZFS boot on zfs mirror
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Andriy Gapon writes:
 > on 26/05/2009 19:21 George Hartzell said the following:
 > > 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
 > 
 > seek=1024 for the second part? and no 'count=1' for it? :-)
 > 
 > [Just guessing] Apparently the first block of zfsboot is some form of MBR and the
 > rest is zfs-specific code that goes to magical sector 1024.

Ok, I managed to read the argument to seek as "one block", apparently
my coffee hasn't hit yet.

I'm still confused about the two parts of zfsboot and what's magical
about seeking to 1024.

g.