The key component in the unified data center is lossless Ethernet, according to FibreChannel and iSCSI advocates. Yet there is a religious war between the two camps on the best way to integrate storage into an Ethernet-based unified data center fabric.

"Everybody thinks that if you go against iSCSI or you go against FibreChannel, you're a bigot one way or another," says Craig Chapman, director of Cisco Unified Computing System strategy at systems integrator MCPc in Cleveland, Ohio. "You can't be a protocol passionista. You can't be tied to one way of doing things. It's, 'What's best for the solution based on what you've seen? And you've got to balance those out."

Chapman says iSCSI does not compete with FCoE as a method for unifying a data center fabric. Both have their place, especially if an enterprise has an installed base of one or the other.

FibreChannel is usually preferred by larger enterprises with a low tolerance for latency and packet loss, and a requirement for high application throughput. But it requires its own infrastructure, which drives up its cost.

Smaller and midsize enterprises might opt for the less expensive iSCSI, which is more latency tolerant than FibreChannel and "lossy," Chapman says.