Virtual Tape Libraries (VTLs) are coming on strong as the backup solution of the future, and they will most certainly play a role in a data center near you very soon. But it would be wise to remember that earlier disk and tape solutions can still be more effective and less costly depending on how they are used and what environment they are in.
There's no doubt that selecting a backup and recovery platform is no easy task, and not just because storage systems in general are growing more complex. The fact is that even mid-sized organizations place multiple requirements on backup systems ranging from length of storage and speed of recovery to any number of deduplication, data compression and data integrity benchmarks.
For those in need of a backup overhaul, a good place to start is this InfoStor Magazine article by NetApp's Adam Fore. It offers a warts-and-all look at all three backup approaches, plus strategies for using snapshots, replication, continuous data protection (CDP) and other tools. His verdict is that VTLs offer a lot of flexibility when it comes to integrating into various storage platforms and is an effective approach to tiered storage, but tape still holds the line on costs, while disk is most suited to rapid-recovery, short-term storage.
For those looking to cut energy costs, however, you have to remember that VTLs are simply a more efficient means of disk-to-disk (D2D) storage. For long-term archiving, tape draws significantly less power and generates less heat than constantly spinning disk arrays.
Still, as the newest technology, it's no surprise that VTLs are seeing the most rapid development, most of it on the appliance level. Overland Storage recently added the REO 9100c system, adding hardware compression to the REO line to extend data capacity from 66 TB to 114 TB. FalconStor has added a pair of VTL appliances, the VTL Storage Appliance and the VTL Virtual Appliance, that work in conjunction to provide enterprise-wide deduplication, as well as 1GB iSCSI or 4 Gb Fibre Channel networking.
For large customers, top-tier vendors are integrating VTL capabilities into full-fledged storage architectures. NEC's grid-based HYDRAstor HS8 supports backup and archival data, bringing VTL and content-addressable storage (CAS) under a single platform.
In general, VTLs do a good job of merging the archival benefits of tape with the speed and flexibility of disk. But for the immediate future at least, it looks like all three still have unique roles to play.