[arch-general] restore hdd image to a bigger disk

[Tavian Barnes]

On 24 August 2010 16:02, Mauro Santos <registo.mailling at gmail.com> wrote:
> On 08/24/2010 10:20 PM, Marek Otahal wrote:
>> On Tuesday 24 of August 2010 23:03:23 Mauro Santos wrote:
>>> On 08/24/2010 08:14 PM, Marek Otahal wrote:
>>>> Hi all,
>>>>
>>>> I use dd command to make an image of entire /dev/sda (160GB) and back up
>>>> it as netobook.hdd to an external storage. The disk contains both
>>>> encrypted(dmcrypt/luks) and normal linux/win partitions.
>>>>
>>>> My question is, if my netbook died and I needed to recover from backup,
>>>> can I just dd-copy the image to a new larger disk? Does it matter?
>>>>
>>>> 1/ it will do, but the size will remain 160gb ..is ok.
>>>> 2/ will do & possibility to resize partitions later ..even better! :)
>>>>
>>>> I've searched the net, but I'd like someone to confirm it 100% works
>>>> (just dd and reboot).
>>>>
>>>> Thanks in advance, Marek
>>>
>>> Most probably you don't even need to copy the image back to a disk to
>>> get the files you need. I don't know about the encrypted(dmcrypt/luks)
>>> partitions but the "normal" linux/win partitions can be accessed
>>> directly from the image.
>>
>> Is that so? I like the restore to a functional computer ability, so copying
>> seems useful. But I was wondering how to mount a specific partition from an
>> image? (i make the image of whole /dev/sda, so sda1,2,..are hidden inside)
>>
>> greetings, Marek
>
> Usually I do it like this:
> - mount (?) the image to a loop device
> losetup /dev/loop0 /path/to/image/file
>
> - get the start of partitions
> parted /dev/loop0 unit B print
>
> take notice of the starting bytes for the partition you want to mount
> mount /dev/loop0 mnt_point -o offset=start_bytes
>
> and thats it, you should be able to access at least the "normal"
> partitions (read and write). I have never tried with encrypted
> partitions, I guess you would have to pass some extra options to mount.
>
> To unmount everything cleanly do:
> umount mnt_point
> losetup -d /dev/loop0
>
> --
> Mauro Santos
>

But why?  The loop module supports partitions now, just modprobe it
with max_part=10 or something.  The partitions will be
/dev/loop0p[1234...].

-- 
Tavian Barnes