Intel touts new data path plan

The architecture has been going by the code name of NGIO (next generation input/output) and is the sequel to the PCI bus, the main data path in a PC that lets computer users plug network cards, disk drives, and other devices into the computer. The PCI architecture is in virtually every Intel-compatible personal computer shipping today and has been for about five years.

The NGIO architecture will be faster and more reliable than PCI, and it has more room for growth, said Mitch Schults, director of marketing in Intel's enterprise server group.

A single NGIO connection would operate at 1.25 or 2.5 gigabits per second, but by binding four channels together, a total bandwidth of 10 gigabits per second is possible--many times the speed of today's PCI bus and plenty of speed to keep up with high-speed "gigabit" Ethernet networks.

In addition, the system naturally isolates devices from the processor and memory, protecting the core parts of the servers from problems in those devices.

NGIO is a technology designed for servers, which typically have heavier needs for fast and reliable data shuttling--referred to as I/O (input-ouput)--subsystems, Schults said. "We've discovered we have squeezed about as much out of the PCI architecture as we can squeeze, where server applications are concerned," said Schults.

But Compaq Computer, among others, believes there's still life in the PCI specification, and has been working with Hewlett-Packard and IBM to double PCI's current top bandwidth with an update called PCI-X.

PCI-X and NGIO don't present an "either/or" choice, said Carl Walker, vice president for technology development at Compaq. Both systems probably will be available at the same time.

But he said Compaq is a little "gun-shy" with new I/O technologies such as NGIO. "We've seen some initiatives that have been less than successful. There are a lot of promises that haven't been delivered."

PCI-X will deliver speeds of 8 gigabits per second, which can "handle almost any foreseeable I/O requirement," Walker said.

Walker also noted that the PCI bus also has longevity because of the reluctance of information system managers to change to new technologies because of all the new testing and troubleshooting required.

Compaq said it decided it "was not in our best interest to participate at this time" in the NGIO forum.

However, about 200 other people are expected to attend the two-day NGIO forum, most of them developers of hardware such as network cards and hard disk "arrays" that plug into computer subsystems, Schults said.

NGIO uses a "switched fabric" instead of the bus architecture PCI uses. With the switched fabric, different components all plug into a switch that can connect the components to the system processor as needed. In a bus, on the other hand, all the components are placed along the same line, and they share the bandwidth available.

One advantage of the switched fabric architecture is that it's more reliable than PCI, Schults said.

"With the basic nature of PCI, when something goes wrong--a card fails, [software] goes nuts, a transaction fails across the bus--the consequences of that failure can be pretty bad in terms of the availability and the reliability of the server system," Schults said. "There's nothing you can do with an extension of PCI to address that fundamental consideration."

With a switched fabric, though, the components are better isolated from the processors, so a failed component won't bring down the main processor, he said. In addition, it has the benefit that it eases the daunting task of swapping out broken components while the computer is still up and running, a process known as "hot-swapping."

Another benefit of the switched fabric architecture is that it lets the processor get on with other work instead of waiting for tasks on the PCI bus to get finished up. "While waiting for the PCI bus to respond, the processor is doing nothing. It's essentially stalled," Schults said. And that problem gets more noticeable as processors get faster. "It doesn't do us much good to be waiting [when a computer is running] at a gigahertz," he said.

With NGIO, the processor would drop a message into a queue and then an Intel chip would handle the task of getting the message through the switch and on to its final destination, allowing the processor to do other productive work.

At the other side of the switch, chips would handle the communication tasks of components such as network cards or SCSI or Fibre Channel disk arrays, Schults said.

Intel will make these "channel controller" chips, and integrate them into the chipsets that support a computers' main processors, Schults said. The first products using NGIO are expected to ship in mid-2000.

Meanwhile, the PCI-X standard is drawing closer to reality, with a final specification expected in the first quarter of 1999 and products in the second half of 1999, Walker said.

Intel was one of the members of the PCI Steering Committee that voted in favor of reviewing and adopting the PCI-X standard, Walker said. The vote was unanimous, he said, so "It's pretty much a foregone conclusion that the industry is going to move forward" with PCI-X. An announcement on the PCI-X's status was planned for today.

Intel is an investor in CNET: The Computer Network, publisher of News.com.