There has been a lot of discussion about Fibre Channel over Ethernet (FCoE), which has recently received major backing from the giants of the enterprise storage vendor world, but this technology remains relatively unknown to end users. Like so many storage protocols before it, the $10,000 question is whether FCoE will take off like iSCSI or fizzle as a niche product like FCIP, DAFS, and so many others. If it does succeed, another critical question is what this means to iSCSI, Fibre Channel, InfiniBand, and to a lesser extent AoE, expanded SAS, and other options for SAN storage.

Why FCoE Matters

With 8 Gb Fibre Channel and alternative storage solutions leveraging InfiniBand now available and iSCSI over 10 Gb Ethernet imminent, many would ask why we need another enterprise block storage medium. In real-world applications, FCoE at 10 Gb will likely deliver roughly the same performance as 8 Gb native FC, but will be one or two years late and (initially) more expensive. Although FCoE will likely be more interoperable than Fibre Channel was in its early years, the lack of support from operating system manufacturers is also troubling. Plus, users will soon be able to build a very similar infrastructure by mixing iSCSI and 10 Gb Ethernet, and this will include all the advantages of IP and solid support.

So why pay more for the same performance from an untested protocol? It’s all about the future, and enterprise users will go where the support is. Storage and network/SAN vendors alike are lining up solidly behind FCoE as the next-generation enterprise interconnect. Although InfiniBand plays Betamax in this home video metaphor, with superior technology and availability, this VHS camp has all the market ammunition. To paraphrase the (alleged) words of Bob Metcalfe, no matter what the technology looks like, the future of networking will be called Ethernet.

The biggest storage vendors are simply because they see that converging and leveraging I/O technology makes sense for them. They can swap out the physical and data link layers from Fibre Channel to Ethernet relatively easily, so the FCoE switch is an easier change than iSCSI. It is likely that they will be able to leverage commodity Ethernet hardware to reduce cost and increase their profit margins once this switch is made. Plus, FCoE will potentially increase SAN attachment rates (and thus enterprise storage market penetration) thanks to the cost efficiency of converged network adapters (CNAs) on the server side. From the storage side, FCoE is all good.

The drive is similar on the network side. The era of differentiated SAN and LAN producers is over - all of the major networking and SAN vendors are repositioning themselves as next-generation I/O providers, setting up a battle in the network space to rival the mainframe shakeout of the 1980s and the PC wars of the 1990s. Converged I/O is the business model for connectivity vendors, and most are taking up the “data center Ethernet” (DCE) charge which includes FCoE as the storage protocol for virtual I/O. iSCSI is still there in a DCE world, but FCoE takes center stage for the enterprise market.

Who Buys FCoE

It may seem strange to declare an upstart like FCoE the winner when established options like InfiniBand and iSCSI are already out in the market, but this examination of the vendors indicates that it is indeed the case. Is this a case of the tail (vendors) wagging the dog (consumers)? Perhaps, but they will come along willingly given the strong case presented by converged and virtualized I/O.

Enterprise buyers are ready for a next-generation SAN technology, and some are beginning to look at 8 Gb Fibre Channel. Those that need performance will certainly buy 8 Gb FC today, but this has little bearing on the overall prospect for FCoE. When an application requires performance and money is available, purchases will be made regardless of future strategy.

Enterprise storage and network architects are beginning to consider the implications of server consolidation and virtualization. As they see footprint shrink thanks to compact or blade servers and server virtualization, they will begin to question the proliferation of interconnects on the back end required to keep up with the I/O demands of these super servers. Already, virtual I/O purveyors like Xsigo are making hay in this market, and, as mentioned above, their SAN and LAN vendors are spreading the message, too. It won’t be long before they are convinced.

Many people mistakenly assume that DCE means pushing all protocols through a single LAN, but this is not the case. These networks will be engineered like SANs from the start, with redundant connections and transparent failover. Although storage and network connectivity will share the same physical “pipe”, they will certainly be segregated on separate VLANs and protected with quality of service technologies. They have to be separated – FCoE (lacking IP) will require a totally different network topology than LAN connections.

Note that, throughout this discussion, I am referring only to the large-scale enterprise data center storage market. Smaller corporate environments have already embraced iSCSI en masse, expanding the penetration of consolidated storage concepts beyond anything Fibre Channel could ever accomplish. And small office and home networks are beginning to embrace these concepts as well, but are relying on protocols like CIFS and AFP for file servers and may begin to look at ATA over Ethernet (AoE) and proprietary protocols like the one pushed by Zetera/NetGear instead of iSCSI. This leaves us with a layer cake of appropriate protocols from the smallest to largest networks. But all have one thing in common: They are all converged and they are all carried in Ethernet packets. Bob Metcalfe was right!