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

[Marek Otahal]

On Wednesday 25 of August 2010 01:02:21 Mauro Santos wrote:
> On 08/24/2010 11:44 PM, Tavian Barnes wrote:
> > 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...].
> 
> Nice tip. I've been using this method for quite a while so either it
> wasn't available when I started using it or I missed the fact that the
> module option is needed for this to work.

thank you very much both of you! I'll use the modprobe w/ max_part argument 
solution. 
-- 

Marek Otahal :o)