Cheap Tricks

A low-cost disk drive technology better known in the PC world is on the verge of showing up in the nation's corporate data centers—if only the technology can shake that PC image.

Advanced Technology Attachment (ATA) is an interface that connects a computer's system bus to disk storage devices. Drives built to the standard, which is also known as Integrated Drive Electronics (IDE), have mainly been used in PCs to date.

But advances in the quality of disks in general—and the long-awaited release of products using a new ATA standard—have prompted vendors such as Hopkinton, Mass.-based EMC Corp., Sunnyvale, Calif.-based Network Appliance Inc. and Blue Bell, Pa.-based Unisys Corp. to put ATA disk drives into corporate data storage devices.

Cost Advantages

"If you're looking at a box that can be sold profitably for 1.5 to 2 cents a megabyte as opposed to SCSI at 3 to 5 cents and Fibre Channel for 7 to 15 cents [per megabyte] for the enterprise, yeah, there are some real price advantages to ATA," says Bob Zimmerman, an analyst at Giga Information Group Inc. in Cambridge, Mass.

Scott Studham, group leader of the molecular science computing facility at the U.S. Department of Energy's Pacific Northwest National Laboratories in Seattle, recently replaced a 20TB tape archiving system with servers that use parallel ATA drives. "It's disk speed at tape cost," he says. "I'm totally in love with this."

Today's parallel ATA drives have a data throughput of 100MB/sec., but a new serial ATA standard will boost that to 150MB/sec. and eventually to 600MB/sec. Serial ATA products are expected to begin shipping in bulk in the second half of next year.

But ATA faces an image problem that must be solved before it will be accepted in mainstream data centers. "You get users saying, 'I don't want that PC desktop disk in my storage environment,' but they have to overcome that perception," says Roger Cox, an analyst in Gartner Inc.'s San Jose office.

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Early Success

Serial ATA disk drives will initially find success in three markets:


1
Host-based internal storage for low-end, Intel-based servers

2
Entry-level network-attached storage

3
Near-line storage or content-addressed storage, which includes systems that store unchanging data such as X-rays, legal documents or checks


ATA disk technology is considered less reliable than SCSI-attached drives because ATA disk drives are tested in batches instead of individually and the mean time between failure is substantially less. But experts are quick to point out that the mean time between failure of today's ATA technology is about 10 to 20 times longer than SCSI-attached disk achieved in the 1990s.


Another issue is that ATA disks are slower than SCSI disks, spinning at 5,400 to 7,200 rpm vs. 15,000 rpm for SCSI.


Even so, with ATA disks at one-third to one-fourth the cost of SCSI-attached disks, analysts say IT managers should be pushing vendors to offer robust ATA storage systems. The problem is that vendors push SCSI and Fibre Channel products "because they give the vendors more of an absolute growth margin," Cox says.


He says serial ATA technology will grow into the data center in much the same way SCSI once did.


"I think serial ATA drive technology is a game-changing technology, and you'll see it deployed in more robust storage environments because, while demand for storage is not changing, the money IT managers have to pay for it is," Cox says.


"Twelve years ago, you didn't see SCSI drives in the data center either," says Roy Sanford, EMC's vice president in charge of Centera products.


In April, EMC announced Centera, an ATA-based RAID array for "content-addressed storage," which creates a unique 27-character identifier for each document or image stored in the system.


Waiting for High-End Gear


According to EMC, ATA disk technology was crucial to keeping Centera's price down to about 2 cents per megabyte.


Several start-ups, such as Atto Technology Inc. in Amherst, N.Y., have also been shipping ATA-based products that have data transfer rates of 2G bit/sec.—the same as Fibre Channel arrays.


Unisys is currently reselling Atto's product as part of its Storage Sentinel array, a RAID controller device that comes in a refrigerator-size cabinet with 2TB of internal storage for the purpose of aggregating storage on multivendor storage-area networks.


As of yet, no vendors have stepped up to manufacture an array that will act as high-end primary storage on the same level as EMC's Symmetrix, IBM's Shark or Hitachi Data Systems Corp.'s Lightning arrays.


"As soon as one of the big guys comes out with a product," Cox says, "we'll see them beginning to be used. I'm looking for a leader."

Special Report

Cheap & Secure Data Stores

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