Storage networks with iSCSI

How it's used: SCSI over IP is a mapping of the dominant language for storage input/output — SCSI — to the dominant network protocol — TCP/IP. Advocates foresee iSCSI becoming an enabler of storage-area networks (SANs) using Ethernet and IP local-area network technology.

Why it's important: Organizations see SANs as a way to improve management, reduce downtime and mitigate ownership costs. SANs based on iSCSI will advance this objective by providing a solution based on familiar IP and Ethernet technologies.

Benefits: ISCSI SANs promise to rectify limitations of the current SAN interconnect protocol, Fibre Channel, which provides no in-band management or security services.

Given the ubiquity of IP networks, the decreasing cost of Gigabit Ethernet switches and administrators' familiarity with IP, iSCSI should be easier and cheaper to deploy and less susceptible to product interoperability issues that have plagued Fibre Channel deployments.

State of the market: Despite lobbying by the Fibre Channel Industry Association to characterize IP as a poor alternative for storage networking, most vendors have promised products based on iSCSI. However, users appear reluctant to deploy the technology before standards are in place and interoperability has been demonstrated.

Areas of concern: The market for iSCSI may be slow to materialize. Many organizations that haven't deployed a SAN will likely adopt a wait-and-see attitude to avoid the potential costs associated with being early adopters. So iSCSI use will likely develop gradually, rather than along the steep curve anticipated by early advocates.