The best way to make a disk dump

Hello, I'm wandering if there is a good way to make a disk dump of my system disk The servers got Two 18Go disk. I do not want to use a Raid system, because I just need to make a dump when all software patches are applied and validated. One solution is to use "dd". One of my friend told me that we can run the following command "cp /dev/sda /dev/sdb" ... to check Is there another good solution.. Note that the second disk is not yet partitioned, so no lilo installed on It ! Thanks for your help Regards Pascal Miquet