OT: Mirroring via disk image file

[Marty <martyb@ix.netcom.com>]

I plan to mirror then replace a hard drive, using an identical model drive.

Instead of a device-device copy e.g. "cp /dev/hda /dev/hdb" I hope to do
"cp <old drive> image" followed by cp image <new drive>" where "image" is
a disk image file of the original drive.

Will the physical sector arrangment be preserved using the intermediate image
file, or is that only possible with the device-device copy?  I'm asking here
because don't have the identical drives available to test my theory beforehand.