How to copy 2 devices byte to byte

From TechnologicalWiki

If you want to copy byte to byte a device or partition, you only need:

Ubuntu / Linux Live CD

[edit] Unmounting and Copy

Start your computer with the live cd on the cdrom drive. Umount the drives or partitions that you like to copy (origin and destination). For example, if you want to copy /dev/sda1 on /dev/sdb1, You can do it typing in a root console:

umount /dev/sda1
umount /dev/sdb1
dd if=/dev/sda1 of=/dev/sdb1

To increase speed always use bs=64k for large files and where you don't need to count blocks.

dd if=/dev/sda1 of=/dev/sdb1 bs=64k

Now, you got a exactly copy of sda1 on sdb1.