Disk backup catches on

The relatively new idea of using groups of low-cost PC disk drives as a staging area for data center backup jobs got a shot of mainstream credibility this month when two well-known names in the storage industry introduced disk-to-disk storage solutions.

The new disk systems — the NearStore R100 from Network Appliance Inc. and the DX30 from Quantum Corp. — are not meant to replace tape libraries as the preferred long-term archive medium. Although tape libraries retrieve data much more slowly, they still cost about one-quarter of the price of the new disk systems for equivalent capacity.

Instead, the vendors are positioning the new disk arrays as "online archive" solutions, providing a sort of temporary holding station for data as it migrates between primary — and very pricey — online disk systems and its eventual off-line resting place on tape.

Among the benefits of having a disk-based middle tier are that backup data can be written to it extremely fast, minimizing the disruption to servers. Perhaps more importantly, backup data can be retrieved just as quickly when data on the primary disks is lost or corrupted, according to Mark Santora, Network Appliance's senior vice president for worldwide marketing.

The concept is appealing to Ben Kobler, a computer scientist at NASA's Goddard Space Flight Center. "[This] would be of great interest to us," he said. "Right now all of our data is really stored on tape. It's too expensive to try and move to disk. As disks become less expensive and we start taking advantage of some of these IDE-type drives, keeping more data on disk to improve processing performance becomes much more viable."

IDE, or Integrated Drive Electronics, refers to the garden-variety disk drives that have been shipping in most PCs for the past 15 years. The newest versions of these drives are also called Serial ATA, or Advanced Tech.nology Attachment, by some vendors. IDE drives cost about one-third or less than the Fibre Channel or SCSI disks that are most common in enterprise storage systems.

The R100 is Network Appliance's first IDE-based product, Santora said. However, he is careful to note that IDE systems make the most sense for the NASA scenario described above. It's an understandable position given that the new systems might otherwise eat into sales of the company's higher priced and presumably more profitable Fibre Channel-based devices.

"When it comes to an application like an online transaction system, Serial ATA just can't do it," he said. "I know my Fibre Channel products will trounce [ATA] in performance and reliability. ATA will probably get to that level in another five to 10 years."

Like all of Network Appliance's storage systems, the R100 uses Redundant Array of Independent Disks technol.ogy to protect stored data. The R100, available now, comes in configurations that scale from 12 terabytes up to 96 terabytes of storage. The 12-terabyte model with software starts at $275,000, scaling up at about 2 cents per megabyte.

Quantum officials say that the DX30, which will initially come in a 3-terabyte model, is in the final stages of testing and will be available commercially in the second quarter of 2002. It also uses Serial ATA drives.

Nexsan Technologies and 3ware Inc. were the first vendors to introduce IDE-based disk arrays about a year ago, but the companies have faced an uphill battle in spreading word about the products' benefits. While they now have help, they also have more competition.

"We really liked the 3ware story when we first heard it, but let's face it: They're a small company, and they just don't have the capital to put together a marketing and sales campaign that will make it a mainstream solution," said Tony Prigmore, senior analyst with Enterprise Storage Group Inc., a market analysis firm in Milford, Mass. "With Network Appliance and Quantum, you clearly now have two of the market leaders. When they go to town with their marketing machines, these are going to become mainstream solutions."