New tape technologies should upgrade backup

Companies thirsting for more robust tape backup systems will have plenty of choices in the months ahead as three tape technologies emerge.

As data accumulates with increasing speed on ever-more-complex networks, systems administrators are under pressure to improve backup systems. E-commerce transactions and other high-volume operations create demand for higher backup storage capacity, faster data exchange and greater flexibility. And, as always, costs must be contained.

The major new technologies that eWeek Labs is watching are Sony Electronics Inc.s AIT-3 (Advanced Intelligent Tape-3); Quantum Corp.s S-DLT (Super Digital Linear Tape); and the LTO (Linear Tape Open) format being developed by Hewlett-Packard Co., IBM and Seagate Technology Inc.

Sony has aimed its family of AIT tape devices at the workgroup and midsize business markets, but AIT-2 tape libraries are also gaining a foothold in the enterprise market, where they compete with DLT-based products.

The spin on AIT

AIT uses helical-scan recording architecture, where data is written diagonally across the tape with multiple heads. This system provides higher data density and speed but is less reliable than linear-scan tape systems because AIT tape wraps around multiple heads and can wear down during high-speed recording. DLT is more widely used in enterprise applications because it excels in the critical mean-time-between-failures factor. As reliability improves with AIT-2 and AIT-3, Sonys technology could gain popularity in the enterprise.

Sony last fall announced plans to ship AIT-3 tape devices in the second quarter of next year. The AIT-1LC tape is designed to deliver increased capacity for the low-end market, which is hungry for cost-effective tape backup.

In midsize companies running automated tape backup with tape devices or autoloader libraries, AIT-2 will be a good choice for adding capacity and reliability. The increases in capacity and scalability provided by AIT-2 and AIT-3 easily justify the higher prices.

The new AIT-3 tapes will have capacities of 200GB with 2-to-1 compression and 100GB native (uncompressed), effectively doubling AIT-2s capacity.

AIT-3 drives will have data transfer rates of 11M bps native and 28M bps compressed. The AIT-3 tapes will also incorporate the remote-sensing MIC (Memory-in-Cassette) chip built into the tape cartridge, but, unlike the AIT-2 MIC chip, the 64-bit AIT-3 MIC can contain more information about the tape, including a tape log, search map and user-definable information.

Sony is designing AIT-3 to be fully backward-compatible with its AIT predecessors, providing an easy upgrade path for AIT users.

At large enterprise sites, Quantums DLT has long been the dominant technology for automated tape backup because of its superior capacity and proven reliability. However, the arrival of LTO and the delivery of better AIT-2/AIT-3 tape autoloaders should change the landscape.

Targeting heavy loads

HP, IBM and Seagate have targeted the enterprise backup market with LTO, an open tape standard based on the linear-scan architecture. As an open standard, LTO has the potential to improve compatibility among storage systems. The standards developers also claim that LTO-based devices will outperform their DLT rivals.

LTO comes in two formats: The Accelis format is designed for fast data access, and the Ultrium format is designed for high storage capacity. Seagate announced plans to ship an Ultrium LTO drive called the Viper 200 at the end of the month that will have native storage capacity of 100GB and transfer rates of 16M bps. The second generation of Accelis LTO-based systems, scheduled to ship next year, will have a 50GB native capacity and transfer rates of up to 40M bps with access time of less than 8 seconds. Second-generation Ultrium LTO systems will have 200GB native storage capacity and 400GB compressed capacity per tape.

Meanwhile, systems based on current DLT technology are being pressed to their limits in high-volume e-commerce environments, so Quantum has turned to S-DLT. The company has yet to announce any S-DLT-based systems, but Quantum officials said that the systems will scale beyond DLT, with a native capacity of 110GB and a transfer rate of 16M bps. They also said that future S-DLT systems will scale to 2 terabytes of compressed storage capacity and transfer data non-natively at rates exceeding 200M bps. By comparison, Quantums current DLT8000 backup system has storage capacity of 40GB native (up to 80GB compressed) with native transfer rates of up to 6M bps.

Given the popularity of DLT, we expect many companies to stick with Quantum and move to S-DLT. However, LTO could be the one to knock DLT off its pedestal because LTOs flexibility could solve nagging compatibility issues.