I/O: The Next Generation

Intel and the Next Generation I/O (NGIO) forum, which consists of Dell, Sun Microsystems, Hitachi, NEC, and Siemens, recently released the 1.0 specification for its proposed replacement of the PCI bus architecture. This specification is based mainly on 2 years of Intel’s work. A competing group consisting of IBM, Compaq, and HP are proposing Future I/O, a variant of this architecture. This second group isn't expected to publish its specification until the end of this year. Although the two specifications aren’t technologically very different, each set of players (especially Intel) wants that control.NGIO specifies a channel-oriented, switched-fabric topology for data transfers between servers, storage systems, and other network systems. When hardware manufacturers implement the new bus architecture, it will be faster, more scalable, and more fault tolerant than current bus architectures. The NGIO specification is currently about 500 percent faster than PCI-66, with a transfer rate of 2.5GBps per wire, multiplied by each wire. The new architecture lets bandwidth increase proportionally to the number of connected devices and provides communications between peripherals without the intervention of the host CPU and bus.In contrast to NGIO, Future I/O is expected to be faster. However, according to the NGIO forum, Future I/O will be eight times more expensive and difficult to implement than NGIO. This competing standard also includes PCI-X, which NGIO does not.The NGIO specification lets vendors build Host Channel Adapters (HCAs), Target Channel Adapters (TCAs), switches, physical links, fabric services, and software to interoperate among different OSs. NGIO products will begin appearing in fourth quarter 2000, with the technology becoming common in 2002.One new addition to the NGIO specification is Sun's Fat Pipes technology. Beyond sixteen 32-channel wires, NGIO becomes throughput limited. Fat Pipes provides additional gains of from 10 to 100 times the throughput of bundling wires by extending NGIO architecture and software, and by providing faster interconnects between peripheral devices. Fat Pipes is in development and will be fully specified in fourth quarter 1999 or first quarter 2000.NGIO’s specification will be the topic of a developer's conference in Newport Beach, California, from September 28 through 30, and is open to members and nonmembers alike. For information about NGIO, go to http://www.ngioforum.org; for more information about Future I/O, go to http://www.futureio.com; and for more information about the PCI standards group, go to http://www.pcisig.com/.