Data centers have traditionally operated a dedicated storage network. This means each server required Ethernet Network Interface Cards and Fibre Channel Host Bus Adapters. With the adoption of 10G Ethernet on the servers, IT administrators are evaluating other options. This has to be done in conjunction with storage array manufacturers because the arrays have to connect into the network somehow. At this point in time, storage arrays are offered with connection at 8G Fibre Channel, 10G iSCSI, 10G Fibre Channel over Ethernet, 10G ATA over Ethernet, and 10G Network Attached Storage.
A dedicated Fibre Channel network has traditionally had an advantage for storage, because it was designed from the beginning to transport SCSI packets fast and reliably. Anything transporting storage over Ethernet has usually had slower performance because protocols had to be put into place to retransmit dropped packets. If the Ethernet network could provide high speed, lossless transmission of SCSI packets with low overhead, it could be a replacement for the Fibre Channel Storage Area Network.
The Nexus Unified Fabric provides upgrades to the Ethernet network to enable high speed lossless transport of Fibre Channel information packets with low overhead through the use of the Fibre Channel over Ethernet protocol. This allows for the gradual elimination of the older and slower SAN. But no organization is going to go out and replace all their existing storage arrays with new ones that have FCoE interfaces on them. So the Nexus 5000 has a special feature that enables conversion from Fibre Channel to FCoE.
The universal ports on the Nexus 5000 allows for any port to have Ethernet or Fibre Channel interfaces. Internally the Nexus Operating System (NX-OS) can map VSAN’s to VLAN’s, and will encapsulate the Fibre Channel traffic into Ethernet frames. To enable lossless transmission of storage at Layer 2 with low overhead, the Nexus switches are set up with Quality of Service to prioritize the storage traffic over all other traffic. This combination of features on the Nexus switches provided for a true datacenter Unified Fabric.
