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Looks like tape, spins like disk

In an interesting twist on the disk vs. tape saga, behold two new sightings on the storage landscape: the Ulysses drive from Imation and RDX, a new technology under development by ProStor Systems Inc., a Boulder, CO, startup. From the outside, both look like tape, but on the inside, each houses a 2.5-inch magnetic hard disk drive.

Imation's Ulysses, which will be generally available in the first quarter of 2006, is for shops that want to add disk to their backup operations, but don't want to add another device into their environment, says John Gaylord, Imation's manager of global product strategy. Using RAID arrays as "an initial place for backups to go" can improve backup performance and restore, he says, "but it introduces additional complexity—it's another target; it's a different medium."

Ulysses uses the LTO Ultrium form factor, and cartridges feature 100GB of capacity. The cartridges fit into a Ulysses tape drive emulator, or drive, which also fits seamlessly into existing tape automation enclosures.

Not only does Ulysses slip unobtrusively into an existing physical backup environment, it also slides in procedurally—there's no need to change backup and restore policies, says Gaylord. "It looks just like a tape except it has the performance characteristics of disk." Ulysses and traditional tape can be pooled, and data from the Ulysses cartridge can be copied to tape using standard tape-cloning commands.

Seamless upgrades are key in enterprise environments, says Molly Rector, director of technical marketing at tape library manufacturer Spectra Logic. Last year, Spectra Logic began selling portable RXT RAID disk packs that fit into its tape libraries. "The kinds of environments that are adding disk to backup typically have very small windows of availability for maintenance," says Rector. "They like the fact that adding RXT is a hot addition to their environment."

The disk-as-tape approach also allows you to ease into disk-based backup. "When you put in a RAID device, you usually have to buy in at a certain level"—typically a couple of terabytes—says Gaylord. But because a Ulysses drive can be as small as the tape drive emulator and a single cartridge, you can buy into disk backup for a relatively small sum and add on incrementally.

When it ships next year, ProStor's RDX will take the disk-as-tape concept one step further, as the cartridges are designed to act as offsite archival media, replacing tape altogether. That's made possible by the rapidly declining price-per-gigabyte of disk, says Steve Georgis, ProStor's president and CEO. "Tape used to have a 100:1 cost advantage, then it was 10:1," Georgis says. "It was only a matter of time before the economics of disk caught up with tape." Next year when the drives ship, Georgis expects RDX cartridges to be priced less than $1/GB vs. approximately $.25/GB for LTO-3 media.

ProStor RDX also addresses concerns about disk's suitability as a removable archive medium. RDX cartridges have a drop-shock tolerance that exceeds that of DLT and DAT tape (a 36-inch drop to hard tile over concrete flooring), and ProStor's Adaptive Archival technology corrects the corrosion and magnetic thermal decay that all disks experience by detecting and isolating bad blocks, and spreading and duplicating data across the surface of the drive.

But drive manufacturers apparently don't think disk is ready to take on the demands of sitting still for a long time. According to Rector, "the feedback we've gotten from them has been a maximum of one year."

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