By Dave Simpson
This month, Intel began shipments of a Gigabit Ethernet adapter that is optimized for iSCSI storage applications, enabling the creation of IP-based storage area networks (SANs). According to International Data Corp., the iSCSI market is expected to ramp up significantly later this year, growing to almost $2.5 billion by 2005 (see chart). Eventually, iSCSI is expected to provide an alternative to Fibre Channel at the low end of the SAN market.
Intel's PRO/1000 T IP storage adapter will compete with a Gigabit Ethernet iSCSI card recently introduced by Alacritech (see Info Stor, January 2002, p. 1). Later this year, other host adapter vendors, including Adaptec, Agilent, Emulex, QLogic, and others, are expected to ship iSCSI cards.
According to Blaine Kohl, marketing director for high-end server connections in Intel's LAN Access Division, the PRO/1000 T uses a "full-offload" design in which TCP/IP and iSCSI protocol processing is offloaded from the host CPU to Intel's IOP310 chipset (which is based on Intel's XScale architecture) and 82544EI Gigabit Ethernet controller. Based on internal tests, Intel claims CPU utilization of 3% to 5% or less. The IOP310 functions as a TCP/IP offload engine (TOE).
The card is priced at $695, or $3,125 in a pack of five.
At the low end, Intel's Gigabit Ethernet iSCSI card will compete with off-the-shelf Ethernet network interface cards (NICs) coupled with iSCSI software drivers. Microsoft, for example, is expected to ship iSCSI drivers later this year. Other than low performance, the drawback to this approach is very high utilization of CPU cycles.
At the high end, the card will compete with iSCSI adapters based on custom ASICs, which are expected to cost more but provide higher performance. Unlike Alacri tech, Intel does not claim "wire-speed" performance (1Gbps in the case of Gigabit Ethernet). However, Intel does claim that its implementation can keep up with the I/O rates of low-end disk subsystems (target devices) at speeds ranging from 300Mbps to 500Mbps.
"The need for wire-speed performance will pick up when end-user adoption of iSCSI picks up in 2003," says Kohl. "By then, you'll have a lot of iSCSI initiators and target devices. The PRO/1000 T is for end users who want to evaluate and test iSCSI solutions."
The iSCSI specification enables the transfer of block-level data over standard copper Ethernet. The standards specification is expected to be completed around mid-year.