dd blows away mbr?

Greetings, all.

I am using dd to copy SAN partitions for system testing and
backup
images.  When I run the following command on my Windows 2003
server boot
partition, the MBR is always blown away.

dd if=/dev/sdc of=/dev/sdd bs=64k

On the Linux system /dev/sdc and sdd are unmounted devices. 
On the
Windows system, a different server, the LUN that is sdc on
the Linux
server is drive C.

If I run the command above to make a copy of the LUN, then
run it
backwards to reimage the saved data back to the original
location, the
Windows machine can't find a bootable drive.  I have to boot
from the
installation CD and get into rescue mode to run fixmbr.exe
in order to
boot the box.  Once the MBR has been replaced, the partition
is
perfect.

What am I doing wrong to miss the MBR?

Or am I?

Thanx!

-Michael


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Michael Weber wrote:
> Greetings, all.
> 
> I am using dd to copy SAN partitions for system testing
and backup
> images.  When I run the following command on my Windows
2003 server boot
> partition, the MBR is always blown away.
> 
> dd if=/dev/sdc of=/dev/sdd bs=64k
> 
> On the Linux system /dev/sdc and sdd are unmounted
devices.  On the
> Windows system, a different server, the LUN that is sdc
on the Linux
> server is drive C.
> 
> If I run the command above to make a copy of the LUN,
then run it
> backwards to reimage the saved data back to the
original location, the
> Windows machine can't find a bootable drive.  I have to
boot from the
> installation CD and get into rescue mode to run
fixmbr.exe in order to
> boot the box.  Once the MBR has been replaced, the
partition is
> perfect.
> 
> What am I doing wrong to miss the MBR?
> 
> Or am I?
> 
> Thanx!

the command looks fine to me, in my ignorance.

Is thh Windows box down at the time? There is no possibility
of a good 
backup being taken while Windows is running.



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John

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Greetings, again!

>>> On 11/10/2006 at 4:32 PM, John Summerfield
<debianherakles.homelinux.org>
wrote:
> Michael Weber wrote:
>> Greetings, all.
>> 
>> I am using dd to copy SAN partitions for system
testing and backup
>> images.  When I run the following command on my
Windows 2003 server
boot
>> partition, the MBR is always blown away.
>> 
>> dd if=/dev/sdc of=/dev/sdd bs=64k
>> 
>> On the Linux system /dev/sdc and sdd are unmounted
devices.  On the
>> Windows system, a different server, the LUN that is
sdc on the
Linux
>> server is drive C.
>> 
>> If I run the command above to make a copy of the
LUN, then run it
>> backwards to reimage the saved data back to the
original location,
the
>> Windows machine can't find a bootable drive.  I
have to boot from
the
>> installation CD and get into rescue mode to run
fixmbr.exe in order
to
>> boot the box.  Once the MBR has been replaced, the
partition is
>> perfect.
>> 
>> What am I doing wrong to miss the MBR?
>> 
>> Or am I?
>> 
>> Thanx!
> 
> the command looks fine to me, in my ignorance.
> 
> Is thh Windows box down at the time? There is no
possibility of a
good 
> backup being taken while Windows is running.
> 
> 
> 
> -- 
> 
> Cheers
> John
> 

Quite correct.  The server is powered off while the backup
and restore
is being performed by a different Linux system.

Any other ideas?

Thanx!

-Michael


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other than the intended recipient(s) is strictly prohibited.
 This 
Confidential Information is intended solely for the use of
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individual(s) addressed. If you are not an intended
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in its entirety, this Confidential Information (and all
copies 
thereof).  E-mail is handled in the strictest of confidence
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Allied National, however, unless sent encrypted, it is not a
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On 11/10/06, Michael Weber <mweberalliednational.com>
wrote:
> What am I doing wrong to miss the MBR?

I don't have an answer to your question, but I'm pretty
interested
into this as well.
It would be great if you could post back to the list if you
find a solution.

Thanks.

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Have you tried copying the MBR separately?  After the
initial backup or recovery 
dd, try:

dd if=/dev/sd? of=/dev/sd? bs=512 count=1

Or if the MBR is static, back it up to a file on backup
host.

I have also heard that cp /dev/sd? /dev/sd? will clone the
disk, but I've never 
tried that, so no guarantee.

And just doing a little free-thinking here, maybe you could
put the two drives 
into a Linux RAID-1 setup and have that handle the syncing. 
You may have to 
destroy and rebuild the array each time.  Again, untested,
just thinkin' out loud.

And while we're talking about RAID, can't Windows do RAID? 
Here's a link to an 
article on using RAID-1 in Win2k3 Server:

http://www.n
etadmintools.com/art439.html

Once again, a method I've never used and I'm not a Windows
admin, but that would 
seem to be the simplest method.  No second OS, no long
shutdowns required.

I don't know what SAN device you're using, but does it do
snapshots?  We have an 
array from 3PAR which is fantastic at this, even allowing
read-write snapshots. 
  I believe NetApps do SAN snapshots as well, but we just
use them for NFS, so 
I've never used the SAN functionality.

--
/* wes hardin */

Michael Weber wrote:
> Greetings, all.
> 
> I am using dd to copy SAN partitions for system testing
and backup
> images.  When I run the following command on my Windows
2003 server boot
> partition, the MBR is always blown away.
> 
> dd if=/dev/sdc of=/dev/sdd bs=64k
> 
> On the Linux system /dev/sdc and sdd are unmounted
devices.  On the
> Windows system, a different server, the LUN that is sdc
on the Linux
> server is drive C.
> 
> If I run the command above to make a copy of the LUN,
then run it
> backwards to reimage the saved data back to the
original location, the
> Windows machine can't find a bootable drive.  I have to
boot from the
> installation CD and get into rescue mode to run
fixmbr.exe in order to
> boot the box.  Once the MBR has been replaced, the
partition is
> perfect.
> 
> What am I doing wrong to miss the MBR?
> 
> Or am I?
> 
> Thanx!
> 
> -Michael
> 
> 
> E-MAIL CONFIDENTIALITY NOTICE: This communication and
any associated 
> file(s) may contain privileged, confidential or
proprietary 
> information or be protected from disclosure under law
("Confidential 
> Information").  Any use or disclosure of this
Confidential Information,
> or taking any action in reliance thereon, by any
individual/entity 
> other than the intended recipient(s) is strictly
prohibited.  This 
> Confidential Information is intended solely for the use
of the 
> individual(s) addressed. If you are not an intended
recipient, you 
> have received this Confidential Information in error
and have an 
> obligation to promptly inform the sender and
permanently destroy, 
> in its entirety, this Confidential Information (and all
copies 
> thereof).  E-mail is handled in the strictest of
confidence by 
> Allied National, however, unless sent encrypted, it is
not a secure 
> communication method and may have been intercepted,
edited or 
> altered during transmission and therefore is not
guaranteed.
> 
> 
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On Mon, 2006-11-20 at 09:21, Wes Hardin wrote:

> I have also heard that cp /dev/sd? /dev/sd? will clone
the disk, but I've never 
> tried that, so no guarantee.

Yes, you can use cp on a raw partition, provided the source
and
destination are exactly the same size.  Been there, done
that for both
ext2/3 and fat. If the destination were larger, most unix
file systems
should cope, no idea what ntfs or fat would do.

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John Morris wrote:
> On Mon, 2006-11-20 at 09:21, Wes Hardin wrote:
> 
> 
>>I have also heard that cp /dev/sd? /dev/sd? will
clone the disk, but I've never 
>>tried that, so no guarantee.
> 
> 
> Yes, you can use cp on a raw partition, provided the
source and
> destination are exactly the same size.  Been there,
done that for both
> ext2/3 and fat. If the destination were larger, most
unix file systems
> should cope, no idea what ntfs or fat would do.

For NTFS use the ntfs tools; Knoppix is good for this. I've
had good 
success copying and resizing ntfs.




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Cheers
John

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On Nov 10, 2006, at 7:58 AM, Michael Weber wrote:
> Greetings, all.
>
> I am using dd to copy SAN partitions for system testing
and backup
> images.  When I run the following command on my Windows
2003 server  
> boot
> partition, the MBR is always blown away.
>
> dd if=/dev/sdc of=/dev/sdd bs=64k
>
> On the Linux system /dev/sdc and sdd are unmounted
devices.  On the
> Windows system, a different server, the LUN that is sdc
on the Linux
> server is drive C.
>
> If I run the command above to make a copy of the LUN,
then run it
> backwards to reimage the saved data back to the
original location, the
> Windows machine can't find a bootable drive.  I have to
boot from the
> installation CD and get into rescue mode to run
fixmbr.exe in order to
> boot the box.  Once the MBR has been replaced, the
partition is
> perfect.
>
> What am I doing wrong to miss the MBR?

The MBR is a 512 byte block at the beginning of the disk. 
You need  
to skip that.

Try this:

dd if=/dev/sd? of=/dev/sd? bs=512 skip=1

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