How to optimize the cloning of a disk with a big empty ext3 partition?

[Gregoire Gentil]

Hello,

I need to duplicate a huge number of identical 8GB SD cards on which I
have 1GB of data at the beginning of the disk on various partitions and
then a 7GB ext3 partition which is rather empty (just a few MB of data).

The duplicator device enables me to select which sectors I can
binary-duplicate. I would love to divide by 8 my duplication time, by
duplicating only the first GB and then the beginning of the 7GB ext3
partition.

When I do a mkfs.ext3, I see that the super-block is written to various
locations of the partition which is not good for the optimization I
would like to do.

Anyone can advise how I could optimize my duplication? What are my
options? Would it be the same situation for ext2? Meaning where is the
journal written on the ext3 partition? Is there a single version or
multiple versions?

Thanks in advance for any answer or pointer,

Gregoire