behaviour after cloning a disk

Nils Kassube kassube at
Thu Dec 22 09:02:26 UTC 2011

Joep L. Blom wrote:
> I want to copy a20GB disk to a partition on a much larger disk (1TB)
> of 20GB. The disk is bootable with 2 primary partitions (1=ntfs,
> 1=ext3) and an extendedn partition with 5 logical partitions (with
> different formats).
> If I copy that disk with "dd if=/dev/sdb of=/dev/sdd8 bs=1024" will
> all be preserved i.e. are all partitions the same as in the old disk
> and is the disk bootable ( and can grub find the bootable partitions
> automagically?).

Yes and no. Everything will be preserved and Grub can't find it (because 
it is more or less hidden). Your dd command copies the entire disk with 
its MBR and the individual partitions onto a single partition. The 
update-grub command, which looks for other operating systems, can not 
see the individual partitions within the copy. It can only sees the MBR. 
It would be rather tricky to find the contents of the individual 
partitions afterwards.

Like J wrote already, you could copy the individual partitions to new 
partitions on the new disk. However instead of using dd it would be much 
easier to use gparted. With gparted you can clone individual partitions 
to another disk. That way you avoid to make individual partitions of the 
correct size for the clones and afterwards grub should find the 
operating systems on these partitions.


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