CommVault Simpana 9 has a really good en scalable VMware VADP integration.
This document describes the best practices to succesfully implement VMware backups.
There are several ways to get the data from VMware to your backup device.
Auto: CommVault determines the best transport available
SAN: Lan-free backup (Luns must be exposed to the MediaAgent
Hot-Add: Virtual solution, adding the disk to a virtual MediaAgent
NBD (ssl): Transport (encrypted) over the network
NAS: Direct backup from NFS datastores
SAN mode is the most efficient and quickest way to backup your VM’s, with Hot-Add you can accomplish a completely virtual solution. NDB should only be used in small environments or when no other option is available.