SCSI Vendors Introduce Next Level Interface

For those IT managers who thought SCSI was holding on for dear life, gasping for its last breath until it drowns in the Fibre Channel, there are some SCSI vendors out there who beg to differ. In fact, these beggars have even brought something to the table by announcing the next-generation SCSI interface, based on Ultra3 SCSI, called Ultra160/m SCSI.

Boasting the ability to double the transfer rate of the Ultra2 SCSI, systems based on the new interface will be available sometime in the middle of next year. Like Ultra3 SCSI, Ultra160/m (m=manageability) will be fully compatible with Ultra2. This backward compatibility is expected to speed the adoption of the new interface by both OEMs and end users.

"The Ultra3 SCSI standard is kind of a smorgasbord of features and vendors can take any of those features and still be Ultra3 compliant," says Sam Sawyer, enterprise product manager, Fujitsu America Inc. (San Jose, Calif., Those features are double edge clocking, cyclic redundancy check (CRC), domain validation, packetization and quick arbitration and select (QAS).

Sawyer explains, "The Ultra160/m SCSI is the combination of the three main components of Ultra3." Double edge clocking allows systems to run faster and increase the reliability. CRC provides extra data protection for marginal cable plants and external devices, ensuring complete integrity of transferred data. Finally, domain validation intelligently tests the storage network to get the right traffic speed. Sawyer says Packetization and QAS features aren't expected to be available for another 2 or 3 years.

Analysts expect Ultra160/m SCSI to extend parallel SCSI technology for use with Windows NT and Unix system workstations, video and Web servers and storage area networks. International Data Corp. (Framingham, Mass.) predicts that parallel SCSI will represent more than 80 percent of the high-end disk drive market in 1999.

In addition to doubling the Ultra2 SCSI data transfer rate, products incorporating Ultra160/m can test and manage the storage network so that the maximum reliable data transfer rate is used. If reliability is believed to be at risk, the transfer proceeds at a lower speed. This "host adaptor intelligence" is expected to provide more system autonomy and less IT manager involvement because the hardware has the intelligence to maneuver at the maximum speed allowed for the system's configuration.

At 160MBps, the new SCSI is so fast, according to Harry Mason of the SCSI Trade Association (STA, San Francisco,, that it offers the same performance as fibre channel. "There's a lot of things to consider about incumbent interfaces," says Mason. "You don't need to use fibre channel for aggregating processor performance." Mason also pointed out market research that states the maximum use of SCSI isn't expected until 2005. "The adoption barriers [for SCSI] are smaller, and return on investment is faster and that's what it comes down to," he says. "We're (STA) not bashing fibre channel but we have a market to attend to and we have SCSI users that want updates."

Fujitsu's Sawyer agrees that the new standardization of SCSI keeps its market ahead of fibre channel. "Ultra2 was a big step forward. With people using that and Ultra3 shipping now, this will slow down the implementation of fibre channel," he says.

Other supporting vendors of the new interface include Adaptec (Milpitas, Calif.,, Hewlitt-Packard Co., LSI Logic Corp. (Milpitas, Calif.,, Mylex Corp. (Fremont, Calif.,, QLogic Corp. (Costa Mesa, Calif., and Quantum Corp. (Milpitas, Calif., -- Brian Ploskina, Assistant Editor

About the Author

Scott Bekker is editor in chief of Redmond Channel Partner magazine.

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