[clug] Recovering disk geometry after whole disk dd

[Michael Still]

Hi.

You might remember my question about copying root file systems to new 
disks from a week or so ago. Well, I'm home now and had a chance to 
actually do the deed. I thought I was being terribly clever, and just 
plugged the new disk in and did a dd from the old disk to the new.

It turns out I'm not nearly as lucky as I thought. That copy worked, and 
the machine is functioning again, but in the process I copied the MBR 
from the old disk to the new disk. This means that fdisk et al now have 
the wrong geometry for the disk.

So, this raises new questions:

  - how can I recover the geometry for the new disk?
  - how can I overwrite just the geometry bits of the MBR with the 
correct information?

Thanks,
Mikal