IBM is unveiling Thursday a new virtual tape drive management system for mainframes that compares to similar technology introduced last spring by rival Sun Microsystems.

The IBM System Storage TS7700 Virtualization Engine is the successor to its TotalStorage Virtual Tape Server and offers increased capacity, faster processing speed and improved disaster recovery features.

Because copying batches of data onto a tape is a time-consuming practice, tying up server operations, virtual storage systems save the data into a disk cache for transfer onto tape at a later time. The TS 7700 offers 6T bytes of disk cache storage capacity, a four-fold increase over the 1.5T bytes of cache in the previous model, said Cindy Grossman, vice president of IBM tape storage systems. An available 3:1 data compression ratio enhances capacity further.

Also, because it operates in a grid computing environment, the 7700 can simultaneously copy data to two different tape storage sites for improved disaster recovery, said Grossman. Data can be "mirrored" to multiple sites and the system will know where to find it.

IBM's announcement follows a similar product launch from Sun by more than five months. In May that company refreshed its Sun StorageTek Virtual Storage Manager System, a tape drive manager also for mainframe environments, which also stores data in disk cache for later copying onto tapes and offers double the capacity and performance of its previous generation technology. Sun acquired StorageTek in 2005.

"These products tend to leapfrog over one another," said Mike Kahn an analyst with The Clipper Group, a research firm in the U.S.

Enterprises are looking for better utilization of their tape storage networks, including improved access to data on them, Kahn said. Storing data to a disk and then later to tape gives enterprises some storage flexibility. If an insurance company receives a claim form, it can save that on disk if it needs to retrieve it quickly while the claim is still active. But if a claim has been completed, that file can be copied onto tape.

The virtual tape storage market for mainframe systems is a two-company market, of Sun and IBM, he said.

The two companies last week each introduced new tape encryption technology one day apart.