For larger businesses there is more to a server backup than keeping a copy of files on another hard drive. You need an application that is capable of tiered backups so that you have ready access to data that needs to be restored as well as off site copies that protect you from fire or malicious intent. Most businesses also have document retention rules. A good backup system is aware of these and keeps documents available for the required amount of time BUT NOT LONGER. This solves a lot of legal problems. For a really good commercial product that will do this consider Netvault. It works cross platform and it has very sophisticated retention and backup rules as well as the ability to manage backups across a large number of servers. It's NOT cheap but worth every penny. And no, I don't work for them. I'm just a very happy customer.