Optical RAID Complements Magnetic - Industry Trend or Event

Computer Technology Review, April, 2001 by Ilona Fass

Optical RAID was designed to utilize optical's well-known archival properties while introducing it to previously inaccessible markets. When Ultera introduced its optical RAID controller in June 2000 it was the product's best chance for a comeback. One year later, the genie still hasn't left the bottle.

Factors leading to optical RAID's inability to mark a strong presence in the data center environment may be threefold: Lack of considerable price point advantage in comparison to magnetic tape, lack of performance advantage, and lack of consumer demand. These deficiencies may have been compounded by the simultaneous technological advancements made in the areas of magnetic tape and hard drive.

Though optical media is a robust, reliable, archival, and efficient way to transport large amounts of data, it is also a slower and more expensive solution than its tape and hard drive counterparts. In the context of RAID, magnetic storage, which used to run 20 to 50 cents per megabyte, dropped to about three to four cents per megabyte, significantly less expensive than optical jukeboxes. Tape runs about three cents a megabyte or less.

Optical RAID was difficult to sell not because the optical media was expensive, but because the drive technology was, according to Michael Schutte, vice president of business development and chief technology officer at Rising Edge Technologies. This was exacerbated by management difficulties. "The eventual bulk of media was considerable, and organizing it got to be scary," Schutte said.

It was exactly this challenge that prompted Plasmon to create and barcode a magazine of 10 disks that fits in RAID 0, 3, and 5 configurations.

The recording speed of a typical tape drive is 10MB/sec and for a hard drive, about 15 to 20MB/sec, depending on whether it is a 10k or 15k drive. The recording speed of optical is a maximum of three to four MB/sec. The highest capacity MO available is 9.1GB per side. With two sides per MO media, it offers a total of 18GB per disk. Tape cartridge, using as an example LTO, has a native capacity of a hundred gigabytes and hard drive has a 75GB capacity. "The commercial economic viability is not there until we come out with higher capacity optical drives," Fred Bedard, senior vice president of sales and marketing at Maxoptix, said.

Given that the price point between magnetic tape and optical has converged, Raidtec users are choosing to do storage on magnetic disk, according to Frank O'Neil, Raidtec's chief operating officer. "If the purpose of RAID is fault tolerance, certainly optical has greater benefits," O'Neil said. "But if the RAID system is performance driven, magnetic is the way to go."

Currently the only optical RAID controllers are produced by Ultera and Rising Edge Technologies. "We ended up doing an optical RAID controller, not because there was a big market but because we already had technology for tape and we just applied it to optical." Mo Nour, president of Ultera said. Their optical RAID controller utilizes multiple optical devices for high performance, reliability, and capacity.

When Rising Edge Technologies produced an optical RAID controller in 1995 it was tailored toward government applications. Over time the durability and archival benefits of optical simply didn't outshine magnetic media. "The cost of the MO drive couldn't keep up with drop in cost of magnetic hard drive," Schutte said.

Rising Edge is currently focusing technology on optical libraries where they also implement magnetic for caching purposes in those systems. "In respect to the NAS market we are finding a need for implementing ease of connectivity into their network," Schutte said. "That's what's helping to open up the optical market, because it's an easier way to get optical storage online and into enterprise wide solutions," he added. Though they do have the technology to support an optical RAID controller, Rising Sun does not offer it as a single product to build new archive solutions.

Over time the increasingly sophisticated technology of magnetic tape seems to have provided enough competition to restrict optical to the realm of backup and support. One example of magnetic outperforming optical is Internet-related. Consider that magnetic is the more common way to access information online. The advantage of magnetic is clear. The most valuable information is kept on a hard disk array because it provides better performance, is more cost effective, and is available with virtually no downtime, according to Rising Edge's Schutte. All signs point to magnetic being the automatic solution for many IT managers, a trend Schutte hopes to change. "We think that other techniques are just as appropriate as magnetic is," Schutte said.

Where optical may be leveraged in the disk array environment is as secondary storage to magnetic RAID devices. "Where optical beats magnetic is in being jukebox ready," says Hal Glatzer, CTR's editor-at-large and a veteran reporter on optical technology. "I think a really good NAS device built around optical would be one that combined both optical and magnetic. On the optical side the jukebox robot could swap disks ad infinitum. Even just flipping them to the B side would double the RAID's capacity right there. Meanwhile, putting the HDD RAID on the front end to the most requested data or file would give users the swiftest possible access times."