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LAN And SAN Unite: Page 3 of 4

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In the very long term, FCoE aims to make converting between Ethernet and FC unnecessary. While the higher-level FC protocol would be retained for its reliability and compatibility with existing storage apps, Ethernet could be used for all storage links. However, that's unlikely any time soon. Storage targets tend to have a slower replacement cycle than network switches, and there's less need to consolidate their links, so most vendors initially plan to use FCoE only for linking to servers. Then FCoE must be converted to physical Fibre Channel, using either a separate appliance or FC modules in an Ethernet switch.

But even when FCoE is ready, Ethernet itself might not be. According to tests conducted by Neterion, the actual performance of many 10-Gbps Ethernet links drops to an average of 4 Gbps once VMware is installed, thanks to the overhead of virtualization. Naturally, the vendor offers its own technology to fix this: extra smarts on Ethernet NICs that are similar in concept to the hardware-assisted virtualization that Intel and AMD have built into CPUs. Until something similar is standard across high-speed Ethernet, people expecting to get full use out of a 10-Gbps pipe may be disappointed.

With InfiniBand also looking to virtualize Fibre Channel, physical FC links to servers look like they may not have much of a future. Still, FC vendors aren't just going to abandon the technology. Though Brocade says it will support FCoE, it's already shipping a Fibre Channel Director intended for network consolidation. "We aim to bring the characteristics of the SAN to other networks within the data center," says Doug Ingraham, senior director of product management at Brocade. His vision is similar to that of Cisco, only it starts with FC instead of Ethernet. And like Cisco, Brocade sees no need to support InfiniBand.

Though storage targets don't have as fast a replacement cycle as virtual servers, they could be in for even greater change once they do. Almost all are based on hard disks, a technology that's already reached its speed limit. Flash memory capacity has grown to the point where it offers a seductive alternative, leading EMC to announce the first high-end storage array based on flash this past January. Its competitors are likely to follow, but flash has important issues that need to be overcome.

The Unified Network

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