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Date:      Thu, 27 Sep 2007 19:09:35 -0400
From:      "Brian A. Seklecki" <lavalamp@spiritual-machines.org>
To:        tradigan@newrevolutions.net
Cc:        freebsd-questions@freebsd.org
Subject:   Re: gmirror
Message-ID:  <1190934575.2982.1.camel@localhost.localdomain>
In-Reply-To: <46934.208.40.168.12.1182968214.squirrel@www.newrevolutions.net>
References:  <46934.208.40.168.12.1182968214.squirrel@www.newrevolutions.net>

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The size colum can be human readable number (ex, "5g") and the offset
can be the name of the previous partition.  For the offset and size of
the first and last partitions respectively use "*".  Read the
disklabel(8) man page for more details -- it is actually a real well
written one.

I wouldn't worry about exact replication -- the sector sizes and total
sectors of the logical gmirror volume and the underlying phyiscal disk
will always be different -- that's the nature of LVM.

Just make them relatively close and match up the letters.

~~BAS

On Wed, 2007-06-27 at 14:16 -0400, tradigan@newrevolutions.net wrote:
> Quick question, I am configuring gmirror to mirror certain slices on my
> hard drives.. I want to mirror /dev/ad0s1 (700M) to another drive.. I am
> fine with configuring gmirror and getting it running but I am unsure of
> how I create the BSD slices with bsdlabel -e..
> 
> When I do a bsdlabel -e /dev/ad0s1 I get:
> 
> # /dev/ad0s1:
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
>   a:   409600        0    4.2BSD     2048 16384 25608
>   c:  1429722        0    unused        0     0         # "raw" part,
> don't edit
>   d:  1020122   409600    4.2BSD     2048 16384 63760
> 
> When I initially create the mirror on the backup disk, I run a bsdlabel -e
> /dev/mirror/gm0s1 and this is what it shows:
> 
> # /dev/mirror/gm0s1:
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
>   a:  1429705       16    unused        0     0
>   c:  1429721        0    unused        0     0         # "raw" part,
> don't edit
> 
> My initial instinct was to mirror the bsdlabel output from ad0s1 but with
> just the 16 offset for the 'a' slice coming out with:
> 
> # /dev/mirror/gm0s1:
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
>   a:  409584        16    4.2BSD     2048 16384 25608
>   c:  1429721        0    unused        0     0         # "raw" part,
> don't edit
>   d:  1020122   409584    4.2BSD     2048 16384 63760
> 
> Is my assumption correct?  Or am I missing something here?
> 
> 
> 
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> 
> 
> 
> 




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