A Virtual Tape Library (VTL) is an emulation of a physical tape library on a disk-based deduplication and compression system such as the DR Series system. The tape library is exposed to a Data Management Application (DMA) as if it is a physical library with tape drives and cartridges, which the application uses for backup. Because a VTL completely emulates a standard library, the introduction of virtual tape is seamless and transparent to existing tape backup/recovery applications. The management of the library, including the drives and tapes, is done by the DMA using SCSI commands. For details on the applications supported, see the DR Series System Interoperability Guide.
The Network Data Management protocol (NDMP) is used to control data backup and recovery between primary and secondary storage in a network environment. For example, a NAS server (Filer) can talk to a tape drive for the purposes of a backup.
You can use the protocol with a centralized data management application (DMA) to back up data on file servers running on different platforms to tape drives or tape libraries located elsewhere within the network. The protocol separates the data path from the control path and minimizes demands on network resources. With NDMP, a network file server can communicate directly to a network-attached tape drive or virtual tape library (VTL) for backup or recovery.