Compaq Presents an Ultra3 Compatibility Strategy

Compaq Computer Corp. put forth a strategy for moving to Ultra3 SCSI devices without leaving Ultra2 in the dust.

Ultra3, based on the Low Voltage Differential Ultra3 version of the SCSI standard, has the potential to double the bandwidth of Ultra2 and can move data at 160 Mbps.

The most significant aspect of Compaq’s strategy is compatibility with Ultra2 devices.

"We’ve been getting a lot of feedback from customers that the rate of technology transitions is overbearing," says Glenn Clownui, director of product marketing at Compaq’s server storage division.

According to Clownui, Compaq’s Ultra3 strategy permits the operation of both Ultra2 and Ultra3 devices in the same server or storage system. For instance, users can take a PCI RAID controller with Ultra3 chips on it, put it in an older ProLiant server that has an Ultra2 system, and the two will work together.

Some of the servers Compaq currently offers, however, will require some minor internal cabling replacements to support both Ultra3 and Ultra2 on a single SCSI bus.

"It can’t be invisible in the sense that you don’t know if its Ultra2 or [Ultra3], but the two are compatible in the sense that they work together in the same system," Clownui says.

Compaq plans to institute Ultra3 into its lines of host adapters, RAID controllers, external storage devices, and server platforms. When these products are enhanced to support Ultra3, the company will refer to them as Ultra3 Ready.

Compaq’s Ultra3 products will be compatible with the company’s Intel-based ProLiant and Alpha-based servers.

Roger Cox, chief analyst for servers and storage at market research firm Dataquest (, says Compaq’s strategy of providing Ultra3 devices that are compatible with Ultra2 technology is vital to the success of the newer standard.

"There could be some compatibility issues between Ultra2 and Ultra3 if it is not handled correctly," he says. "Compaq is big on providing legacy compatibility."

Compaq’s Clownui admits that compatibility issues may arise, and the actual transmission speeds won’t always reach 160 Mbps.

"There is an opportunity cost involved with doubling the bandwidth, but it has to be done properly," he says.

Although Compaq had only revealed this strategy at press time, at least two vendors, Hewlett-Packard Co. and Mylex Corp. (, already announced products based on the technology.

HP released the Kayak XM600 and XU800 PC Workstation families -- select models of which ship with Ultra3 SCSI -- for dual-channel SCSI and FASTRAID capabilities.

Mylex is now offering the eXtremeRAID 2000, a member of Mylex's new Ultra 160 SCSI controller family of enterprise-class RAID controllers, and the AcceleRAID 352, an entry-level Ultra 160 SCSI controller.

Compaq’s Clownui says his company will begin shipping nonpluggable Ultra3 disk drives for entry-level servers this month. In the first quarter of next year, Compaq plans to offer hot-plug versions of the drives.

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