Windows Azure Online Backup (WAOB) originally only allowed customers to backup files that didn’t require the use of a VSS writer. As such, this left out SQL, Exchange, and system state data (and others). Since then, WAOB has been extended to allow DPM servers to utilize it for short term protection of the DPM protection groups.
This means that the DPM VSS writer is used when protecting data in this fashion.
NOTE: This extension of WAOB functionality only works with DPM 2012 SP1.