Restoring Data from a DD image

Bill Schmitt (SW) software at schmittnet.com
Thu Oct 6 13:16:41 PDT 2005


Gayn Winters wrote:

>>-----Original Message-----
>>From: owner-freebsd-questions at freebsd.org 
>>[mailto:owner-freebsd-questions at freebsd.org] On Behalf Of 
>>Bill Schmitt (SW)
>>Sent: Thursday, October 06, 2005 11:11 AM
>>To: questions at freebsd.org
>>Subject: Restoring Data from a DD image
>>
>>
>>I've just replaced a hard disk that was dying fast. I've done a full 
>>installation of 4.9 (later releases won't install, which I've 
>>submitted 
>>a problem report on already). The old disk is connected but 
>>not mounted. 
>>Searching around, I found some suggestions to try to read the 
>>old disk 
>>to restore what I can and I used dd to copy what could be found (dd 
>>-if=/dev/ad0s1e of=/usr/olddsk/oldimag.dmg conv=noerror,sync) and it 
>>seems to have copied the file. Now, I'm a little stuck. Can 
>>someone help 
>>me understand how do I mount that image somewhere to browse 
>>it and copy 
>>what I can from it? If I'm not going about this the right way, I'd 
>>appreciate other suggestions
>>
>>    
>>
>
>I'm a little confused:
> 
>Did you try to copy (dd) the old disk before you did a new install?  
>If so, to where?
>
>Is /dev/ad0 your new disk with the fresh 4.9 installation on ad0s1? Or
>did you just add a new disk as /dev/ad1 and did the fresh install on
>ad1s1?
>
>Is your unmounted old disk /dev/ad0 or /dev/ad1 now?
>
>I'm guessing that ad1 is your new install, ad0 is not mounted, and you
>were able to copy ad0s1e to oldimag.dmg with the above dd command.  If
>so, continue. If not, send a correction.
>
>Why not try 
>   mount -r -t ufs /usr/olddsk/oldimag.dmg /mnt
>   cd /mnt
>   ls
>
>I ***think*** mount will do this.  If not, try dd'ing oldimag.dmg to a
>spare slice, e.g. if you created /tmp as /dev/ad1s1e, then you could
>   dd if=/usr/olddsk/oldimag.dmg of=/dev/ad1s1e
>   cd /tmp
>   ls
>
>Good luck!
>
>-gayn
>
>
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>
>
>  
>
Sorry, when I first decided to try FreeBSD, I had a 4.7GB as the primary 
on ad0 and moved usr to ad1 when I added the drive that ultimately went 
bad (a 60GB) as ad1. When I had to do a full installation again, I put a 
new drive (80GB) into place where the 4.7GB drive was and started from 
scratch with ad1 disabled. So, now I'm booting from the new drive and 
have used dd to copy whatever is found on the damaged ad1 to an image on 
ad0. It's after that I get stuck. I've looked at the man page for mount, 
but  I haven't seen anything specific to an image. I tried your 
suggested mount command, but it responded "Block device required". I 
suppose I can try to dd back to the 4.7GB drive that I would now mount 
as ad1. We'll see what happens.

Thanks,

Bill



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