Adaptec pushes "EtherStorage" spec

Posted on June 01, 2000


By Dave Simpson

Paralleling an effort by IBM and Cisco (see story on this page), Adaptec has submitted to the Internet Engineering Task Force (IETF) a proposed standard for running SCSI-over-TCP/IP networks such as Gigabit Ethernet. The goal of the proposal is similar to the IBM-Cisco effort, and most parties expect the various standards efforts to converge over the next few months.

Also participating in Adaptec's "EtherStorage" proposal are vendors such as 3Com, Hewlett-Packard, IBM, and Quantum.

"Our goal is to enable the use of cost-effective storage area networks in a broader market via Ethernet," says Mark Lohmeyer, marketing manager in Adaptec's storage networking solutions group. He says that target companies include cost-conscious sites and companies that have a large infrastructure built on Ethernet.

However, as with other efforts to run SCSI over TCP/IP networks to create Gigabit Ethernet SANs, reality may be a few years away. Nevertheless,

Adaptec plans to ship EtherStorage-compliant products in mid-2001, including a host bus adapter and a bridge product with an EtherStorage attachment on the front end and Fibre Channel or SCSI attachments on the back end. The technology was demonstrated at last month's Networld+Interop show.

Click here to enlarge image

Adaptec is positioning the SCSI-over-TCP/IP technology as being complementary to Fibre Channel SANs. "In the future, Ethernet-based storage and Fibre Channel will compete, but if you want to build a SAN today, Fibre Channel is the only way to go," says Lohmeyer. (Adaptec's Ethernet move comes shortly after the company re-entered the Fibre Channel market via a partnership with Agilent Technologies and the acquisition of DPT.)

Lohmeyer also says that Adaptec's proposal is complementary to the IBM-Cisco proposal. Both IETF groups are working on standardizing a SCSI encapsulation protocol. Functionally, the two methods are the same, but they differ in implementation. Both groups hope to agree on a single standard.

As with the IBM-Cisco SCSI-over-TCP/IP proposal, one big stumbling block is the poor performance of the TCP/IP stack. Lohmeyer says that there are two options to overcoming the stack overhead and CPU utilization problems. One is to implement the TCP/IP stack in hardware on network interface card (NIC) accelerators. The other approach is to use a lighter-weight transport layer that's optimized for storage traffic in a SAN environment. Tackling the latter option, Adaptec is developing a SAN transport protocol (STP) that would provide an alternative to TCP (see diagram).

"You could use different transport layers for different applications," says Lohmeyer. "For example, TCP/IP for WANs or an STP-like protocol for local SANs."

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