How to copy a disk - Linux

Here are the steps which shows

How to copy a disk over network .

Copy a disk over network , target machine enter following command:

"nc" utility and "dd" are used to copy a disk over network

nc -l -p 6565 | gzip –dfc | dd of=/dev/hdb

And on source machine.

dd if=/dev/hda | gzip –cf | nc 192.168.75.21 6565