In many organizations, tape emerged as a primary backup mechanism for the simple reason that it was much less expensive than disk storage. However, enterprises never liked using tape very much -- it was slow, the media was often unreliable, and maintaining tape libraries was a labor-intensive task.
Consequently, many companies have been on the lookout for a better option. With the steady decline in prices for disk storage, it has become a replacement for tape at some companies. Virtual Tape Libraries (VTLs), which mimic tape backup systems while storing information on disk, deliver the robust features found with a tape backup system while eliminating tape's shortcomings.
As a result, the VTL market has been growing at a rapid rate. International Data Corp. (IDC) found that worldwide revenue increased from $830 million in 2007 to $930 million in 2008. In recognition of that trend, many vendors have moved into the VTL arena. Dell, EMC, FalconStor, HP, IBM, NetApp, Overland Storage, Quantum, Sepaton, Spectra Logic, and Sun are some of the companies in this space.
Corporations and vendors have invested a great deal of time, effort, and money designing efficient tape backup systems. VTLs enable companies to continue to rely on tape backup software but write information to disk rather than to tape.
Falling disk pricing has been the main driver behind the migration to VTLs. In the past, disk cost 20 or more times as much as tape for the same capacity. Recently, technical advances have lowered that gap, so disk commands only three to four times as much as tape. Because it is much simpler to deploy and maintain, disk has become a potential tape replacement for more companies.