What you need to know about 10 GigE IP SANs

Rick Cook provides an overview of the state of 10 GigE today, outlines the benefits and limitations of 10 GigE and offers some insight into the future of IP storage networking.

What you will learn: This tip provides an overview of the state of 10 GigE today, outlines the benefits and limitations of 10 GigE and offers some insight into the future of IP storage networking.

If faster is better for storage area networks (SAN), 10 Gigabit Ethernet (GigE) is the next logical step up. It is beginning to arrive, but it is still definitely in the early adopter stage.

10 GigE is defined under the 802 standard (802.ae) and uses the same MAC protocol, frame sizes and format as regular Ethernet. However, unlike the older versions, it doesn't rely on the Carrier Sense Multiple Access/Collision Detect protocol (CSMA/CD) to prevent network contention because all connections are full duplex.

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Ultimately, the promise of Ethernet iSCSI SANs is integration. By using Ethernet for LANs, WAN and storage area networks (SAN), companies theoretically can simplify infrastructures, improve management and reduce costs. While some companies are moving in that direction, the effort has been hindered by the fact that the current standard is 1 GigE, which is much too slow for many applications.

You can buy 10 GigE IP SANs today from a few vendors, such as Nimbus Data Systems, Intransa and Lefthand Networks. However, many of the vendors are small and the products are still new.

Today, 10 GigE SANs are most attractive for what analysts call "corner cases" -- users with highly specialized needs. Among the early adopters have been media companies that need to move a lot of large files, firms looking to back up server farms using a D2D strategy and a few places looking for a very high bandwidth path between servers.

For the average user, there are cost and connectivity issues that detract from 10 GigE's' potential. Even though 10 GigE offers the promise of lower cost SANs, prices are currently considerably higher than for Fibre Channel and 1 GigE Ethernet. Connectivity is hampered by the fact that most servers today are not 10 GigE ready, although adapters are available.

Another key element in 10 GigE's adoption is cabling. The early versions relied on fiber cable, however, 10 GigE can use copper cabling. Cat 5e unshielded twisted pair can be used over a distance of about 180 feet. Augmented Cat 6 and regular Cat 7 shielded twisted pair works for up to 300 feet. Meanwhile, optical cable connections can reach up to 25 miles, compared to 3 miles for 1 GigE.

Some enterprises are looking to the future by installing 10 GigE compliant cabling in upgrades or new construction even though they are still using 1 GigE.

Meanwhile, work on 100 GigE moves forward, albeit slowly. The latest hitch is a division in the IEEE committee defining the standard between those who want to go directly to 100 GigE and a group that wants to insert a provision for 40 GigE into the specification. In any event, it will probably be at least five years before 100 GigE (or 40 GigE) enters the SAN market.

About the author: Rick Cook specializes in writing about issues related to storage and storage management.

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