In an effort to prove the viability of storage area networks (SANs) based on the emerging iSCSI standard, three vendors demonstrated a configuration running at "wire speed" over Gigabit Ethernet. Participating in the demo were Alacritech, Hitachi Data Systems, and Nishan Systems.
iSCSI is an IP storage standard under development in the Internet Engineering Task Force (IETF) that can complement and/or provide an alternative to Fibre Channel SANs. The standard is expected to be finalized around midyear.
In the demo, a server with Alacritech's "1000x1 Server and Storage Accelerator" card was attached to a Nishan 4300 storage switch, which, in turn, was connected to a Fibre Channel-based Hitachi Freedom disk array. Alacritech's I/O card offloads TCP/IP and iSCSI protocol processing from the host CPU. (For more information on iSCSI and Alacritech's TCP/IP offload engine [TOE] card, see ATA puts the squeeze on SCSI and iSCSI SANs inch closer to reality.)
The server-to-switch connection was clocked at 219MBps--the "wire speed" of Gigabit Ethernet. However, participants acknowledged that the test was based on Intel's Iometer benchmark code, which does not reflect real-world application performance. Nevertheless, officials from Alacritech and Nishan claim that iSCSI performance will be comparable to that of Fibre Channel. It should also be noted that the 219MBps speed was achieved in full-duplex (bidirectional) mode.
"iSCSI allows end users to mix and match IP and Fibre Channel architectures, or to use an all-IP storage configuration," says Barry Hauser, vice president of marketing at Alacritech. Another advantage of iSCSI, according to proponents, is that it lets IT shops leverage existing infrastructure (TCP/IP networks) and expertise.
In addition to purportedly providing a lower-cost alternative to Fibre Channel, iSCSI is also expected to benefit applications such as storage consolidation, business continuance, remote backup and restore, and remote data access.
But the key to the demonstration was performance. "Wire-speed performance makes iSCSI suitable for a wide range of storage applications," says Tom Clark, director of technical marketing at Nishan. However, iSCSI performance in real-world application environments has yet to be proven.
In addition to achieving wire-speed performance (with benchmark code), the tests demonstrated a relatively low CPU utilization--slightly less than 8%--due to the TCP/IP offload capability of the Alacritech card. The card, which Alacritech refers to as an integrated storage network interface card (IS-NIC), is priced at $999 and can be used in network-attached storage (NAS) and SAN configurations.