History
The first VTL solution was an IBM Virtual Tape Server (VTS) introduced in 1997. It was targeted for a mainframe market, where many legacy applications tend to use a lot of very short tape volumes. It used ESCON interface, and acted as a disk cache for 3494 tape library. A competitive offering from StorageTek (acquired in 2005 by SUN Microsystems, then subsequently by Oracle Corporation) was known as Virtual Storage Manager (VSM) which leveraged the market dominant STK Powderhorn library as a back store. Each product line has been enhanced to support larger disk buffer capacities, FICON, and more recently (c. 2010) "tapeless" disk-only environments.
Other offerings in the mainframe space are also "tapeless". DLm has been developed by EMC Corporation, while Luminex has gained popularity and wide acceptance by teaming with Data Domain to provide the benefits of data deduplication behind its Channel Gateway platform. With the consequent reduction in off-site replication bandwidth afforded by deduplication, it is possible and practical for this form of virtual tape to reduce Recovery Point Objective /RPO and Recovery Time Objective /RTO to approaching zero (or instantaneous).
Outside of mainframe environment, tape drives and libraries mostly featured SCSI. Likewise, VTLs were developed supporting popular SCSI transport protocols such as SPI (legacy systems), Fibre Channel, and iSCSI.
The VTLs currently being adopted by Open Systems (including AS400 series) are dominated by FalconStor Software Inc. The FalconStor VTL is the foundation of nearly half of the products sold in the VTL market, according to an Enterprise Strategy Group analyst.
Read more about this topic: Virtual Tape Library
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