VCB is Vmware consolidated backup a utility from which allows backup applications to take online snapshots of running Linux and Windows Guest virtual machines hosted on VMware ESX or ESXi servers. VCB then allows those snapshots to be moved to a separate system known as a “VCB Proxy Server” to be backed up “off-host” from the ESX host server by a backup application, such as Backup Exec 12.5, without impacting the ESX host server and all of its Guest virtual machines during a backup
AVVI agent doesnot include the VCB, you cannot use the AVVI agent without VCB as that is utility which will all the backup software to take the snapshot of the VM's
If u have a VM ware server that should not cost u . u can download it using the link http://www.vmware.com/download/vi/drivers_tools.html
How do I obtain VCB from VMware and how much does it cost?
Answer- VCB is actually free and is included in all versions of ESX 3, including Foundation,Standard, and Enterprise editions, as well as ESXi. The VCB framework package can then be installed directly on a Windows server to enable it as a “VCB Proxy Server”.
For moreinformation on VCB licensing, please visit http://www.vmware.com/products/vi/cb_buy.html