snapshot backup - how it works

Hi,  I am wondering how do you backup snapshots from a storage. I heard you have to mount it somewhere on a storage node and then back it up. Also I heard that  a snapshot is seen in the networker as a saveset. Now here are my questions:  How do you technically "mount the snapshot" for backup purposes? is it something like mounting a LUN from storage and then you see this as a normal filesystem and you back it up like any other filesystem? Or does the storage node see "a SCSI target" and backs up "some stream of bytes"?  I am asking because we have received a request to backup a farm of servers in hosting environment with 2 TB of files each. About 20 servers. And our concerns are about the amount of files on each server and the time networker needs for full backup. Currently we are backing up storage nodes with ~16 millions files with local disks of 800 GB and this takes 12 hours. I presume that on those 2 TB there will be even more files and the backup process will take much longer if the backup of a snapshot is like backing up a normal file system.  Any usefull thoughts on this subject would be appreciated. :)  Bartosz Maruszewski