Tape technology stretches out

Tape technology stretches out

Like many IT executives, Eric Eriksen, chief technology officer at New York-based Deloitte Consulting, would like tape to just go away. The added cost of managing tape backup systems, slow and unreliable restoration, cartridge inventorying and off-site storage headaches have him hoping that cheap disk drives may someday replace 50-year-old tape technology in the data center.

"We only need tape for cases when we can't restore from disk. It's a necessary evil," he says.

Yet despite a drastic shift toward low-cost Advanced Technology Attachment disk arrays for backing up business data, there's no end in site to the use of tape in the data center -- especially for archival storage. Administrators may complain, but tape still has an enormous intalled base and remains 10 to 50 times less expensive than disk. It's also very secure, since data stored off-line on removable media is physically inacessible to hackers and viruses.

And vendors and analysts say evolutionary advances in the basic technology in midrange tape drive systems, improvements in management tools, and the emergence of combined disk/tape subsystems are likely to answer some user complaints -- and keep tape technology in data centers for at least another decade.

Bigger and Faster

Manufacturers of the three leading midrange tape drive technologies -- digital linear tape (DLT), linear tape-open (LTO) and advanced intelligent tape (AIT) -- are preparing significant capacity and speed improvements. Advanced drives, including SuperDLT (SDLT), SuperAIT (S-AIT) and LTO Ultrium 2 (LTO-2), are the latest variations. Each uses half-inch tape and offers roughly five times the capacity and performance of standard DLT, AIT and LTO tapes.

For example, DLT was developed in 1986 and the average cartridge originally held about 96MB of data. SDLT today holds 160GB. Over the next decade, SDLT will grow to about 2.5TB native capacity with 250MB/sec. throughput. LTO, which derives its name from its open architecture, could grow to 10TB native capacity by 2011.

Vendors say 1TB tape cartridges could appear as early as next year. Tape manufacturers such as Quantum Corp., Certance LLC and Storage Technology Corp. expect tape to more than meet future needs. That's a tall order, since the amount of data produced by the average enterprise is doubling every year, according to Stamford, Conn.-based Gartner Inc.

To keep up, tape media will evolve to have more than 1,000 tracks and a thickness of 6.9 microns (about as thick as cellophane). And it will also work with drives that write on both sides of the tape, says Jeff Laughlin, director of strategy for the automated tape solutions unit at StorageTek in Louisville, Colo.

In contrast, StorageTek's current high-end tape drive, the proprietary T9940B, uses 200GB, one-sided tape that has 576 tracks and is 9 microns thick. Laughlin expects transfer rates to keep up with the larger capacity tapes as well. "There's more money being spent on tape media research than ever before in history. You're going to see greater transfer rates at the head interface, transfer rates of 100GB/sec., 200GB/sec.," he says.


Emerging management software that can monitor the health of tape drives, Fibre Channel switch port connections to libraries and even the tape cartridges themselves will help ensure that users are able to restore from tape, more easily manage backups and predict problems and backup failures, vendors say. Advanced Digital Information Corp. (ADIC) and Quantum, for example, have recently introduced native management software tools on their tape libary and drive technology.

ADIC sells all major tape cartridge technologies in its automated libraries and tape autoloaders, but Dave Uvelli, an executive director at the Redmond, Wash.-based company, says he believes cartridge formats and drive technologies are becoming irrelevant. Instead, ADIC is betting on new, intelligent tape library systems that will eventually provide detailed information on drives and tape, whether it's related to a downed switch port, a stuck drive or a tape cartridge that's reaching the end of its life.

One example of archival intelligence is ADIC's Scalar i2000 tape library. Introduced in early July, the Scalar i2000 is designed to eliminate the need for an external library control server. Among other things, the system can send backup failure alerts via pager or e-mail, partition a library into multiple logical libraries and perform mixed media, performance and proactive system readiness checks.

In July, San Jose-based Quantum also introduced DLTSage, a suite of predictive and preventative diagnostic tools that run on its SDLT tape drives to help ensure that backups have completed successfully. The applications can also tell administrators when drives have reached critical thresholds for capacity and predict where and when errors may occur.

Here Come the Hybrids

While disk-to-disk backup is already popular, during the coming year, manufacturers plan to introduce more hybrid systems that combine disk with tape libraries in storage-area networks for faster backups and restores and easier archiving. ADIC, for example, plans to introduce a combined tape/disk library this month.

"You won't just have tape. One could imagine RAID-protected disk where I/Os from the backup job are completed at (wire) speed while the (library) robot, through management software, stages it on tape drives for archival," says StorageTek's Laughlin.

Ultimately, however, scalability and restorability will continue to be the key criteria to take into account when selecting tape systems, says Deloitte Consulting's Eriksen. "We're looking for a single solution that can cover everything, regardless of the needs we have," he adds.

Choosing the Right Format

Will the SDLT, LTO-2 or S-AIT tape drive technology you're using today be around tomorrow? Most likely, vendors and analysts say, although some users are finding reasons to switch from one format to another.

Even with software advances in SDLT, more users are buying LTO-2 drives these days. Bob Amatruda, an analyst at Freeman Reports in Ojai, Calif., says LTO-2 appeals to users because its open architecture offers a choice of vendors. Hewlett-Packard Co., IBM and Costa Mesa, Calif.-based Certance all manufacture LTO-2 products, whereas only Quantum produces DLT and SDLT drives.

In July, Quantum put self-diagnosing intelligence into its SDLT drives, a move that analysts say will help boost sales. Quantum also says it has plans for at least four more incarnations of SDLT, and the vendor has 31 percent of the overall tape market -- more than any of its competitors.

But John Pearring, president of StorServer Inc. in Colorado Springs, a manufacturer that sells all three tape technologies, still gives LTO the edge. "LTO is open and makes more sense, and it's 200GB native (vs. 160GB for the latest SDLT 320 drives)," he says.

Deloitte's Eric Eriksen says he's looking at moving from four HP tape libraries, with eight SDLT drives each, to a single HP or ADIC Scalar 10K tape library using LTO drives for greater capacity in a smaller footprint. He says his decision isn't being driven so much by LTO-2's openness, but by its compression rates and speeds, which -- for the moment -- exceed those of SDLT. He also says that the new LTO-2 libraries are more scalable than his older system.

"One of the things that's important when we're doing streaming across multiple tape drives is to be able to restore quickly," he says, referring to LTO-2's 200GB capacity and 35MB/sec. throughput.

That doesn't matter to Phil Andrews, director of high-end computing at the supercomputing lab at the University of California, San Diego. He has avoided LTO Ultrium because he says it lacks the track record of reliability that he requires. "We've looked at LTO, but we have to be conservative because we're holding a lot of people's data here," he says.

And while LTO has a capacity and performance edge over SDLT today, analysts say the two tape technologies continuously leapfrog each other in capacity and throughput, so other factors may be more important.

SDLT and LTO-2 may be neck and neck in speeds and feeds, but Sony Electronics Inc.'s S-AIT leapfrogged both with the vendor's introduction of a 500GB, 30MB/sec. drive in December -- and it's likely to remain ahead for some time, based on current SDLT and LTO road maps (see graphs, below).

S-AIT also has the edge in pricing: S-AIT tape cartridges are US$80, vs. US$120 for LTO-2 and $130 for SDLT. Sony intends to develop and support S-AIT through at least a sixth generation, says Stephen Baker, vice president of storage solutions at Sony in San Jose. But S-AIT's appeal has been limited because, as with SDLT, only one manufacturer produces the drives.

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