In the open systems world, the comparatively new de-duplication (de-dupe) capability typically saves 95% of data space for disk backup copies and for remote replication and 80% on data archiving. This (along with lower cost SATA disk drives) has drastically altered the economics when comparing the costs of backing up on disk versus directly to tape. However, de-dupe has not been available for mainframe systems up to now.
Virtual tape library (VTL) technology was initially an entirely separate development and is designed to divert to disk backup output destined for tape without the server backup operation being aware. The immediate benefit is in speeding up backups, which helps accommodate shrinking backup windows, and also to reduce recovery times (and especially for partial recovery where only part of the backed up information needs to be re-established). Backed up data residing on disk also remains accessible in real-time. In a VTL system, output to the physical tape drive or library will normally occur as a background or off-line process afterwards.
Yet it was when de-dupe began to be built into VTL backups so as to drastically shrink the backup disk footprint that VTL's attraction to large enterprises greatly increased. QuickRecover software and the series of hardware components which it manages were developed in order to make VTL with de-dupe available to mainframe (IBM z/OS) systems for the first time.