VADP – vSphere storage APIs for Data Protection. This is a VMware API that backs up and restores vSphere virtual machines (VMs). As VMware explains; a backup product using VADP can backup vSphere virtual machines from a central backup server or virtual machine without requiring backup agents or requiring backup processing to be done inside each guest virtual machine on the ESX host. This offloads backup processing from ESX hosts and reduces costs by allowing each ESX host to run more virtual machines.
Data Protection uses vSphere’s snapshot capabilities to enable backup across a SAN without requiring downtime for virtual machines. As a result, backups can be performed non-disruptively at any time of the day without requiring extended backup windows and the downtime to applications and users associated with backup windows.