As we’ve been selling more and more SANs to complement our Cisco UCS solutions, there has been one overwhelming revelation that I didn’t expect: iSCSI is going to win over Fibre Channel (FC).
For a long time, if you wanted a SAN, and you wanted high performance, then you invested heavily in FC. It guaranteed performance from the server to the SAN by having dedicated FC cards in the server attached to dedicated FC switches. The SAN had its own little network to guarantee this performance. FC started out at 1Gbps, then 2, 4, 8, and now I’m hearing 16Gbps. This sounds great, except when you look at the stats: 95% of SAN users need less than 2Gbps in performance. Most of us just don’t have large data centers that demand this upper level of performance.
iSCSI, on the other hand, is Ethernet based. It takes SCSI data and puts it into a TCP/IP packet and then wraps it in an Ethernet frame to transmit it down the wire. In the past, it was hard to guarantee performance unless we used separate Ethernet switches just for the SAN. As Ethernet networks have improved in performance, this issue no longer exists. Today, with 10Gb Ethernet lossless Ethernet networks, we can demonstrate that the iSCSI network has guaranteed performance. And, with 10G, the speed and bandwidth available far exceeds what we typically need. Now we can implement iSCSI storage networks for a fraction of the cost of a Fibre Channel storage network and yield the same, if not better, results.
If you have Fibre Channel today, it may make sense to keep it for now. But the next time you replace your SAN, it’s definitely worth considering iSCSI. If you are new to buying a SAN, I would only consider iSCSI, especially if you are implementing a 10Gb network.