A virtual tape library (VTL) provides a cost-effective addition to their disk-based backup. By storing data to disk rather than tape, the VTL speeds data backup and retrieval without requiring users to change their existing backup processes. This is because, to the backup server and backup application, the VTL looks like a traditional tape library. Benefits include squeezing ever-larger data sets into tight backup windows, retrieving data quickly when required for legal or regulatory reasons, and reducing the operational and reliability risks related to tape.