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Date:      Tue, 3 Aug 2004 09:37:05 -0400
From:      Bill Moran <wmoran@potentialtech.com>
To:        Matt <finitesoup@gmail.com>
Cc:        questions@freebsd.org
Subject:   Re: using a disk "mirrored" with dd
Message-ID:  <20040803093705.6dec1f13.wmoran@potentialtech.com>
In-Reply-To: <1e490997040802231017bc78bf@mail.gmail.com>
References:  <1e490997040802231017bc78bf@mail.gmail.com>

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Matt <finitesoup@gmail.com> wrote:

> I have a machine running 4.10-RELEASE-p2 with two identical hard disks
> -- ad0 and ad2. I would like to make a complete copy of the first disk
> to the second disk nightly for quick disaster recovery.
> 
> I've dd'ed the disk as follows
> 
> # dd if=/dev/ad0 of=/dev/ad2
> 
> and edited the disklabel of the second disk to change ad0s1 to ad2s1 as follows
> 
> # disklabel -e -r ad2
> 
> However, I'm still unable to mount the root partion (or any other
> partition) of the second disk to tweak /etc/fstab etc. even though
> 
> # mount /dev/ad2s1a /mnt
> mount: /dev/ad2s1a: Operation not permitted

What is your securelevel?  See man securelevel.

> 
> What am I missing? Is there anything else I need to do beyond editing
> the disklabel to allow me to use the "mirrored" disk?
> 
> Output of disklabel for the two disks follows:
> 
> # disklabel ad0
> # /dev/ad0c:
> type: ESDI
> disk: ad0s1
> label: 
> flags:
> bytes/sector: 512
> sectors/track: 63
> tracks/cylinder: 255
> sectors/cylinder: 16065
> cylinders: 4864
> sectors/unit: 78156162
> rpm: 3600
> interleave: 1
> trackskew: 0
> cylinderskew: 0
> headswitch: 0           # milliseconds
> track-to-track seek: 0  # milliseconds
> drivedata: 0 
> 
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
>   a:   409600        0    4.2BSD     2048 16384    97   # (Cyl.    0 - 25*)
>   b:  5242880   409600      swap                        # (Cyl.   25*- 351*)
>   c: 78156162        0    unused        0     0         # (Cyl.    0 - 4864*)
>   e:  4194304  5652480    4.2BSD     2048 16384    89   # (Cyl.  351*- 612*)
>   f: 10485760  9846784    4.2BSD     2048 16384    89   # (Cyl.  612*- 1265*)
>   g: 18874368 20332544    4.2BSD     2048 16384    89   # (Cyl. 1265*- 2440*)
> 
> # disklabel ad2
> # /dev/ad2c:
> type: ESDI
> disk: ad2s1
> label: 
> flags:
> bytes/sector: 512
> sectors/track: 63
> tracks/cylinder: 255
> sectors/cylinder: 16065
> cylinders: 4864
> sectors/unit: 78156162
> rpm: 3600
> interleave: 1
> trackskew: 0
> cylinderskew: 0
> headswitch: 0           # milliseconds
> track-to-track seek: 0  # milliseconds
> drivedata: 0 
> 
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
>   a:   409600        0    4.2BSD     2048 16384    97   # (Cyl.    0 - 25*)
>   b:  5242880   409600      swap                        # (Cyl.   25*- 351*)
>   c: 78156162        0    unused        0     0         # (Cyl.    0 - 4864*)
>   e:  4194304  5652480    4.2BSD     2048 16384    89   # (Cyl.  351*- 612*)
>   f: 10485760  9846784    4.2BSD     2048 16384    89   # (Cyl.  612*- 1265*)
>   g: 18874368 20332544    4.2BSD     2048 16384    89   # (Cyl. 1265*- 2440*)
> 
> Thanks for any insight, and let me know if you need to see anything else.
> 
> -Matt
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-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com



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