[SWLUG] Taking a disk image

[Justin Mitchell]

On Fri, 2007-01-26 at 15:01 +0000, Bradley, Peter wrote:
> But will it back up my Windows XP Pro partition, my two Linux partitions
> and the boot sector all in one go, such that I can restore from the
> external medium and then boot from the original hard disk, find grub and
> see my original OS options and be able to then boot into either?
> 
> Sorry, I'm not doubting you or anything.  I just want to be totally
> clear.
> 

doing something like:  dd if=/dev/hda of=/dev/hdb
where:
 hda == original disk, master first controller
 hdb == replacement disk, slave first controller

dd is doing a raw disk copy, by naming the whole disk device (/dev/hda)
it is copying absolutely everything. mbr, partition tables, the lot.
it knows nothing of the format

you have to make sure the target disk is the same size or bigger than
the source otherwise this isnt going to work.

after its copied you can edit the partition table and (using the right
tools) can usually resize the partitions to fill the new bigger disk,
but initially everything will be exactly as it was