Commvault Simpana is a very powerful backup suite. One of its many features is the ability to protect your VMWare environment. It can do so in 3 ways, which I will describe here.
VMware backups normally use a Virtual Server Agent, normally referred as a VSA, to backup your VMs. This VSA can be a physical box or as virtual machine. It will use either vStorage API for Data Protection, VADP, or VMware Consolidated Backup, VCB, depending on what method your VMware environment supports.
There are 3 main methods of protecting your VMware environment. These are SAN Backup, HotAdd, and NBD.
Also known as “Lan-Free Backup”, this VMware backup method requires the VSA to have a SAN connection to the luns hosting the virtual disks directly. This will allow the backup to be performed over the SAN. Only some administrative commands are sent over the LAN from the VSA host to the ESX server. This sort of backup is only possible when your VSA host is a physical server.
This method requires you to install the VSA on a virtual machine on the ESX server. To backup the VMs, the volumes are directly mounted on the VSA host. This treats the virtual disks a local disk for backup. If a VM is located on a different host, then the VSA host will need to have access to the other data stores in the VM cluster.
This backup method is the slowest of the three, so it is usually used as a failsafe method, normally when there is a problem with the SAN backup or HotAdd methods. The VSA host will directly talk to the ESX server over the TCP/IP network and backup the VMDK file. In sensitive environments, NDBSSL can be configured to encrypt the network traffic to provide added network security.