[sf-lug] use dd for backups question

Kristian Erik Hermansen kristian.hermansen at gmail.com
Mon Nov 19 23:07:12 PST 2007

On Nov 19, 2007 9:13 PM, jim stockford <jim at well.com> wrote:
>     imagine a machine with two hard disks, both
> with identical geometries (same make, same
> model...).
>     one is a dual boot disk with both windows and
> some linux distro as the first scsi drive.
>     the other is blank in the second scsi position.
>     imagine booting the box from a live CD and
> using the dd command to copy absolutely
> everything from the bootable disk to the blank
> disk. something like
> # dd if=/dev/sda of=/dev/sdb bs=512
>     imagine powering off the box.
>     imagine pulling out the first scsi drive and
> replacing it with the second scsi drive.
>     imagine powering on the box, and please let
> me know what you imagine happens (I imagine
> that the box comes up as usual: would it?).

I don't see why you need the 'bs=512' option, but OK.  I think I
researched this one time and chunking into 512 bytes does not speed up
the dd writing to disk in any way.

I imagine that it would work, yes, unless you have problems mounting
via fstab.  I mean, any hardware-related info that has tainted the
software config could be an issue.  Device serial numbers, etc.  For
instance, it is possible that Windows could be using the hard drive
serial number as a variable in the activation algorithm.  If you try
to boot Windows on this new drive, it could be a problem.  I have read
papers that say this is highly unlikely and that you need to change
three minor components for this to happen -- like new RAM, disk, and
video card for instance.

Either way, it should otherwise work correctly...
Kristian Erik Hermansen

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