dd of xfs partition does not mount

["Chris Croswhite" <ccroswhite@xxxxxxxxxxxx>]

Hello,

I was trying to dd a drive that has several partitions with several file
systems.  I am having dificulty getting the xfs partitions on the dd'ed
drive to mount properly. Here is what I am doing:

dd if=/dev/hda of=/dev/hdb bs=1024

Then I try to mount the one xfs partition:

mount -t xfs /dev/hdb4 /mountpoint

All other dd'ed partitions I am able to mount.  I have tried this on
several machines with the same affect.  What am I doing wrong?

TIA,
Chris