GigaLabs extends SCSI, offers Fibre Channel alternative
Going against the grain of Fibre Channel fervor, GigaLabs Inc. last month began shipping a SCSI switch that may cause some companies to rethink their potential migration from SCSI to Fibre Channel. GigaLabs, in Sunnyvale, CA, is well-known in the supercomputing arena for its high-speed HIPPI switches. The company`s SCSI-based Jigsaw storage networking switch can handle both bus and protocol switching in a device with latency times of less than one microsecond.
According to GigaLabs officials, one potential advantage of the SCSI switching approach, versus a whole-hog migration to Fibre Channel, is that it would allow companies to preserve their existing investment in "legacy" SCSI equipment.
Implemented in a non-blocking crossbar switch fabric, the Jigsaw 8 provides an eight-slot chassis with a backplane capacity of 12.8Gbits per second, or 1.6Gbps full-duplex bandwidth per slot. In addition to SCSI, the switch supports ATM and HIPPI. Support for Gigabit Ethernet and Fibre Channel is due in the third quarter, according to Kon Leong, GigaLabs president.
Analysts expect GigaLabs` SCSI switch to loosely compete with products from vendors such as Computer Network Technology (CNT) and Bus-Tech Inc.
Although analysts applaud the technological achievement, some doubt whether GigaLabs can successfully swim against the rising tide of Fibre Channel supporters who advocate a migration from older SCSI technology to the emerging Fibre Channel. "One of the problems GigaLabs might have is that the momentum is behind Fibre Channel, and they`re in a small corner trying to promote SCSI, although their approach does make sense from a technology standpoint," says Dennis Waid, president of Peripheral Research Corp., a market research and consulting firm in Santa Barbara, CA.
GigaLabs may be able to carve out a niche while other vendors focus squarely on Fibre Channel. "GigaLabs has a nice market niche in maintaining the installed base of SCSI, and all the Fibre Channel vendors are ignoring it," says Tom Lahive, senior industry analyst at Dataquest, a market research firm in San Jose, CA. Lahive points out that more than 95% of the new subsystems shipped this year will come with Ultra SCSI host interfaces, and that Fibre Channel will probably not become dominant until late 1999.
Targeted at applications such as remote backup, disaster recovery, long-distance clustering, remote mirroring, and data warehousing, the Jigsaw switch overcomes some key limitations of the traditional shared-bus SCSI approach, such as cable length and the number of devices that can be connected on a bus.
By cascading Jigsaw switches, users can connect devices at up to 20 kilometers over private fiber, or over unlimited distances using ATM. That compares to a 6-meter cable limitation for single-ended SCSI, or 25 meters for differential SCSI. Device counts in a switched environment can exceed 122,000, according to GigaLabs officials. SCSI is currently limited to 16 devices per bus.
In addition to the speed improvements, the features of switched SCSI put it in direct competition with Fibre Channel loops and fabrics. Fibre Channel supports up to 126 devices per loop, with--eventually--cable distances up to 10 kilometers (although 3 kilometers is the current limit.)
GigaLabs` Leong contends that "the most compelling case for Fibre Channel is speed [100MBps per loop], but SCSI is going to 80MBps, and to 160MBps later this year [via a specification from the ANSI X3 T10 committee]. SCSI is catching up very quickly."
The time frame for delivery of 180MBps SCSI, a.k.a. SCSI-3, is under question. "Even if [ANSI] comes up with an approved spec in the first half of the year, it`ll take another quarter or two until suppliers integrate it into their equipment," says Lahive.
Leong also points out that as you add devices to a Fibre Channel-Arbitrated Loop (FC-AL) configuration, latencies can significantly degrade performance. One more potential problem for early users of Fibre Channel, according to Leong, is incompatibility between devices from different vendors and between devices with different operating speeds (e.g., quarter-speed vs. full-speed--1Gbps--Fibre Channel implementations).
The Jigsaw 8 is available through resellers at $7,000 to $8,000 per port. Leong says that GigaLabs next month will introduce a beta version of a SCSI switch targeted at the Windows NT market for around $2,000 per port. Leong says he plans to "meet or beat" Fibre Channel switch prices at the low end of GigaLabs` SCSI switch product line.--DS