Virtual tape libraries (VTL) can dramatically improve the performance of tape-based backup/restore (B/R) applications (e.g., improved RTO, de-duplication of backup data). Nonetheless, physical tape systems generally will still have to be employed for archiving applications and moving copies of production data to disaster-safe secondary sites (unless shops secure enormous and costly bandwidth for moving backup data between primary and secondary sites).
VTLs, then, are unlikely to obsolete tape. However, VTLs will reduce the count of tape drives required in a shop. Since restore (time to read data from tape) requirements typically demand far more tape drives in operation than backup requirements (time to write data to tape, which often can be performed asynchronously), fewer tape drives will be demanded in VTL shops. Fewer drives, though, does not necessarily translate into less media, despite VTL de-duplication. The Wikibon community believes that data written to tape for movement to secondary sites is best written in full form, with duplicates, to minimize the degree to which VTL or de-duplication technologies increase the complexities of recovery efforts at the second site in the event of a disaster.
Action Item: VTLs will reduce the number of tape drives required to handle backup, restore, disaster management, and archiving applications, but will not obsolete tape for the foreseeable future, nor reduce the volume of tape media required.