Virtual Tape Library

A virtual tape library is a disk based storage system that emulates physical tape drives units. With functionality similar to Tape backup, but with the backup operations executed at disk speed, a virtual tape library can significantly shorten your backup windows.

As most virtual tape libraries today are using Data Deduplication, the disk size requirements of the RAID arrays where the virtual tape library resides are greatly reduced. As a result, the cost of the disk storage is reduced, together with energy consumption. Virtual tape libraries are used also in the process of replicating data offsite for disaster recovery (DR) purposes, reducing bandwidth requirements by means of the same technology of data deduplication. In this case, the cost of the target disk storage is reduced as well, together with energy consumption at that location, making data deduplication a "greener" technology than the conventional disk systems.

Choosing a Virtual Tape Library

Scalability: As a mature technology, a tape backup modular unit scales easily. You can increase the backup storage capacity by adding rack modules. Thus, to compete successfully with the tape backup units, a virtual tape library should also scale easily. This means that it must have the ability to add disk capacity, as the storage requirements are increasing.

The virtual tape library is used for data backup on the faster, short-term disk storage system, ensuring fast immediate restores. If the virtual tape library will have to push the backed-up data to tape drives, it should be able to connect to your tape drive units, and to send the data in the format of the tapes you are using. This is important for archiving purposes, as the tape is the choice for long-term storage.

The virtual tape library should be able to handle encryption, assuming that the backup software is already doing that.

As the backup software vendors have acquired a solid experience with tape backup systems, it makes sense that they extended their support for virtual tape libraries, which are emulating tape drives backup.

Vendors are working together to integrate their technologies. Symantec’s OpenStorage program is integrating backup systems and virtual tape libraries. The company initiated a program named Symantec Technology Enabled Program (STEP), which allows partners to gain access to Symantec's OpenStorage API. This way they can integrate their technologies with Symantec's Backup Software, Veritas NetBackup.

One drawback of a virtual tape library is that data deduplication technologies are pretty much proprietary. If you use a virtual tape library to replicate offsite, and than you need to restore the non-deduplicated data elsewhere, then you are tied up to the same vendor, and you need to have the same type of virtual tape library at the other end.