By Dave Simpson
After a delay of more than a year, Adaptec has begun shipments of an ASIC-based host bus adapter (HBA) that fully offloads both iSCSI and TCP/IP protocol processing from host CPUs. The HBA will compete with iSCSI cards from Alacritech and Intel and, later this year, QLogic, Emulex, and others.
iSCSI HBAs enable end users to build block-level SANs using standard Ethernet-TCP/IP networks and switches. HBAs that offload protocol processing from host CPUs via dedicated ASICs provide a higher-performance alternative to using only iSCSI software drivers (although iSCSI performance still lags behind the performance of Fibre Channel SANs).
Performance is application-dependent and depends largely on the size of the blocks being transferred, but Adaptec officials claim throughput rates of around 130MBps (full duplex) in early testing.
According to Glenn Clowney, director of OEM product marketing in Adaptec's Storage Networking Group, the "killer apps" for iSCSI will initially be backup and recovery (including disk-based backup), and storage consolidation in application environments such as Microsoft Exchange, SQL Server, and Oracle databases.
Adaptec is shipping the iSCSI HBAs through distributors and resellers at suggested retail prices of $660 (for the model 7211C copper version) and $715 (for the 7211F fiber version), although "street" pricing could approach $500. The cards are under evaluation by various OEMs. Software drivers are available for Windows NT/2000 and Linux.
The full-offload capability of Adaptec's HBAs differentiates them from designs based on "partial offload" technology (such as Alacritech's), which typically require more CPU cycles. And the use of dedicated ASICs for hardware-based acceleration differentiates Adaptec's HBAs from iSCSI cards based on network processors (such as Intel's). Like all iSCSI cards, Adaptec's adapters include a TCP/IP offload engine (TOE).
Adaptec's iSCSI adapters are compatible with Microsoft's iSCSI architecture for Windows, which is due next month. Microsoft's iSCSI framework will enable management of IP SANs via Windows Management Instrumentation (WMI) and supports the Internet Storage Name Service (iSNS) for clients and servers.
Early beta sites for the iSCSI HBAs include Sandia Labs, the University of Michigan, and Trimble Navigation, a developer of global positioning system (GPS), optical and laser positioning technologies.
Trimble's IP SAN, in its Dayton, OH, data center, includes a Network Appliance filer attached to one Linux server and three Windows servers, each of which is equipped with Adaptec's 7211 iSCSI adapters. All systems are connected via a Gigabit Ethernet LAN.
According to Shawn Wilde, Trimble's director of global IS operations, the company considered a Fibre Channel SAN as well as standard network-attached storage (NAS), but Fibre Channel proved too expensive and the iSCSI solution provides better price performance than a NAS solution. Wilde says that the iSCSI SAN provides "very, very close to Gigabit Ethernet speed." Trimble runs a mix of applications on the IP SAN, including Microsoft Exchange, Oracle databases, and engineering applications.
The 7211C and 7211F HBAs are based on an Adaptec ASIC that Cisco uses in its Fibre Channel over IP (FCIP) Port Adapter for its 7200 and 7400 storage routers, which enable companies to connect Fibre Channel SANs over long-distance TCP/IP networks.