By Richard R. Lee
Start-up veteran Larry Boucher (founder of companies such as Adaptec and Auspex) has launched a new company called Alacritech. The company's sole charter is to boost TCP/IP performance in network-attached storage (NAS), iSCSI and other IP-oriented storage technologies that use Gigabit Ethernet as the infrastructure.
Alacritech has developed the first of many "Session Layer Interface Cards" (SLICs) that vendors such as NetConvergence and others have been waiting for to fill in their iSCSI implementations. The SLIC cards are specialized network interface cards (NICs) that have an on-board processor for speeding up TCP/IP operations, thereby freeing up CPU cycles that are typically lost in processing TCP/IP commands in software, by off-loading the protocol stack in hardware.
Alacritech's NICs are based on the company's Internet Protocol Processor (IPP), a chip built around a core CPU optimized for protocol operations. The NICs work in tandem with the CPU's TCP/IP stack to support the processing of "fast path" streams of non-exception-type transactions.
The impact to the CPU in regard to offloading networking operations can be dramatic. According to ZD Labs, CPU loading can be reduced as much as 80% over conventional NICs. Much of this is accomplished by the way that the SLIC examines and processes entire blocks of data and then moves them into system memory (as opposed to examining every single packet, as conventional NICs do). This reduces the shuffling of packets, as well as improving bandwidth performance. Additionally, the saturation of the CPU with TCP/IP traffic becomes almost non-existent, with transfer rates approaching wire speed (1Gbps).
In the ZD Labs tests, which compared Alacritech's 100x4 adapter with Intel's PRO/100+ adapter, the CPU utilization for the Alacritech adapter was 22%, compare to 100% with the Intel adapter. ZD Labs reported that the Alacritech adapter throughput peaked at 872Mbps, and the Intel adapter peaked at 425Mbps.
Alacritech is also pursuing opportunities for the technology in the emerging 10Gbps Ethernet arena. Company officials believe that their technology offers a unique path to supporting 10X packet rates over today's Gigabit Ethernet, while reducing CPU loading significantly.
The NICs are expected to be priced significantly lower than Fibre Channel equivalents (generally, less than ½ the price), and this will be a critical factor as the storage industry begins to choose between iSCSI and Fibre Channel for storage area network (SAN) infrastructures.