VCB proxy (VMware Consolidated Backup proxy) is the server that collects virtual machine (VM) backup data from VMware Consolidated Backup (VCB).
VCB, a component of VMware Virtual Infrastructure 3 (VI3) and vSphere 4, takes virtual machine snapshots and mounts them to the centralized VCB proxy server in read-only mode. Using a proxy server takes backup processes off of the ESX/ESXi host servers, eliminating the backup agents traditionally used in physical infrastructures. IT shops can use one or more proxy servers to back up a VMware virtual environment. The VCB proxy must be able to access all storage-area network logical unit numbers that have VMs.
A backup agent installed on the VCB proxy archives the file data using whatever storage media the user chooses. Because the proxy server presents this data as if it were as locally attached, the backup agent only has to run on the proxy server and not on the ESX/ESXi hosts. The VCB proxy can run as a physical standalone server or inside a virtual machine. When the proxy server is a VM, VCB can optimize the I/O path for backups with hot-add transport mode.