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Review: Host Bus Adapters

Don't connect your servers to an iSCSI SAN without dedicated iSCSI host bus adapters. The $500 to $600 you spend on a HBA will take a load off the servers' CPU, and give you the storage speed of Gigabit Ethernet. Although prices have remained about the same, this year's accelerators are easier to install and configure than the first-generation devices we tested last year.

The iSCSI platform provides a reasonably priced alternative to 2-Gbps Fibre Channel for block-level access to large storage arrays. This hybrid of SCSI and TCP/IP offers a simple yet high-performance alternative to FC at a low cost. What's more, it has tremendous growth potential, particularly now that 10-Gbps Ethernet--a natural fit for iSCSI--is on the horizon.

True, high-performance FC still dominates mass storage, but its speed comes at a price: You'll pay 50 percent more in TCO for an FC SAN, compared with the cost of an iSCSI SAN, by our accounts. Even FC HBAs cost more. QLogic's 2310F 2Gb FC HBA has a street price of $1,030, for example, while the company's Gigabit Ethernet iSCSI card lists at $679. Further, FC components often are incompatible, and the complex process of configuring and maintaining FC SANs often requires adding admins to your staff or getting outside support.

An accelerator isn't mandatory, of course, but encapsulating SCSI instructions and data and handling the TCP/IP stack is CPU-intensive. The HBA's processing power lets you reap iSCSI's rewards by off-loading that overhead. Our previous tests showed that though iSCSI could run on fiber or copper Gigabit Ethernet hardware, reasonable performance could be achieved only through the use of a dedicated and accelerated iSCSI HBA. Overall CPU utilization dropped from more than 20 percent for bidirectional transfers to less than 5 percent and remained at that level for all but the most computationally intensive operations.

We asked seven vendors to send us iSCSI HBAs for testing in our Green Bay, Wis., Real-World Labs®. Three accepted our challenge. Returning players Adaptec sent an updated version of its 7211C iSCSI card and Alacritech sent the SES 1001 iSCSI Accelerator. New to the lineup is QLogic's QLA4010 SANblade, which was in development during our last tests. We also invited Astute Networks, Emulex, Intel and Xiran. Emulex's product was still in the OEM qualification stage, Intel didn't respond, and Xiran was closed by its parent company, SimpleTech, on June 16. Astute Networks says its multiport cards work as iSCSI targets in the storage device, rather than initiators in the server.

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