However, in some cases server virtualization can reduce the number of backup licenses. This is a nice benefit. You don't have to run as many agents as in the past, and you can save some money there.
In some environments, server virtualization has prompted the use of a secondary storage system, for example, a disk-to-disk backup system to maintain multiple copies of images.
Check out the entire Virtual server backup FAQ
This was first published in January 2008