The StorageTek Virtual Tape Library (VTL) Appliance from Sun combines the vendor's servers, SATA disk arrays, controllers, and software to emulate tape libraries and drives. The appliance, which ships in configurations now encompassing from 4U to 4 full racks, presents to existing tape-based backup and recovery software an emulated tape environment; i.e., existing tape software sees the appliance as a tape library or tape drives, to which it can write data to and read data from. Beneath the virtualization layer, however, the appliance uses SATA disk arrays to perform RAID protected storage and recovery of data.

Sun lists three families of VTL appliances on its site: The original VTL appliance line, the VTL Plus line, and the new VTL Value appliance.

The original VTL appliance offerings are based on the vendor's FlexLine controllers and FLC200 disk arrays; providing performance ranging from 300 to 900 MB/sec, depending on version (three primary configurations are offered).

The Plus line of appliances, which the vendor has stated will eventually replace the original VTL appliance line, utilizes Sun's 6140 and 6540 controllers and arrays and Sun Fire servers for increased performance and capacity. Additionally, supported tape emulations are also expanded; Plus appliances can emulate drives including DLT, SDLT, LTO, StorageTek T9840, StorageTek T9940, and StorageTek T10000; as well as tape libraries including the StorageTek L series and the SL500/SL8500.

Three configurations of the VTL Plus Appliance are available:

- The VTL1140 which occupies a full 19 inch rack, is based on the 6140 controller, and provides from 8-56 TB of raw storage space. The 1140 includes two 2 Gb/sec FC ports for host connections; supports the emulation of up to 16 tape libraries, 128 tape drives, and 2,048 tape cartridges; and supports data rates of up to 400 MB/sec.

- The VTL2540 which occupies from one to four full 19 inch racks, is based on the 6540 controller, and provides from 8-224 TB of raw storage space. The VTL2540 includes 8 2 Gb/sec FC ports for host connections; supports the emulation of up to 64 tape libraries, 512 tape drives, and 4,096 tape cartridges; and supports data rates of up to 700 MB/sec.

- The VTL3540 which also occupies from one to four full 19 inch racks, is based on the 6540 controller, and provides from 8-224 TB of raw storage space. The VTL3540 includes sixteen 2 Gb/sec FC ports for host connections; supports the emulation of up to 128 tape libraries, 1,024 tape drives, and 8,192 tape cartridges; and supports data rates of up to 1400 MB/sec.

Optional software features available for the VTL Plus appliances include IP replication, tape caching (support for the policy-based migration of disk volumes to physical tape), Secure Tape (physical tape encryption), NDMP support, and support for IBM iSeries/AS400 host servers.

New to the vendor's VTL product line is the VTL Value appliance, a single-configuration 4U rackmount model targeted to SMBs. The VTL Value is based on the vendor's Sun Fire X4500 server with the ZFS file system; a four-way x64 platform with 24 TB of storage (48 500 GB drives). 2 2 Gb FC ports are provided for host connections; and the appliance supports the emulation of up to 16 tape libraries, 128 tape drives, and 1,024 tape cartridges. Throughput is listed at 250 MB/sec.

Like the VTL Plus line, software options for the Value appliance include compression/encryption (within ZFS), tape caching, physical tape encryption, and support for NDMP. All but the ZFS compression/encryption and NDMP support are listed as "coming soon."

The Sun StorageTek VTLs are available now. The new VTL Value appliance is priced at $84,995; VTL Plus offerings start in the $135,000 range.

Contact Sun Microsystems for further information.