This is part of an ongoing series of longer articles I will be posting every Sunday as part of an experiment in offering more in-depth content.
There has been a lot of discussion in the storage industry about Fibre Channel over Ethernet (FCoE), making it the toast of Storage Networking 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 for iSCSI, Fibre Channel, InfiniBand, and to a lesser extent AoE, expanded SAS, and other options for SAN storage. The enterprise data center is poised for a complete change in server connectivity, with 10 Gb Ethernet converged network adapters (CNAs) and new core switches carrying both network and storage traffic, and this holds promise, especially in virtualized environments. But CNAs do not equal FCoE, and iSCSI, conventional Fibre Channel, and other protocols are roaring ahead. What impact will FCoE really have?
Why FCoE Matters
With 8 Gb Fibre Channel and alternative storage solutions leveraging InfiniBand now available (and with 10 Gb iSCSI 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 FCoE will be one or two years late and (initially) more expensive. Although active standards participation and “plug fests” mean FCoE will likely be more interoperable than Fibre Channel was in its early years, the lack of support from operating system manufacturers is 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 market goes, just as wide availability of VHS tapes buried Betamax. Storage, network, and 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, FCoE’s 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 behind FCoE 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 (their, not your) cost and increase profit margins once this switch is made. Plus, FCoE will potentially increase SAN attachment rates (and thus enterprise storage market penetration) thanks to the potential availability of converged network adapters (CNAs) on the server side, and the cost-effectiveness that sharing a CNA between network and storage implies. 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 (also called “converged enhanced or enterprise Ethernet” or CEE) which includes FCoE as the storage protocol for virtual I/O. iSCSI is still there in a DCE world, but FCoE will take center stage for the enterprise market.
Counting the Benefits of FCoE
It may seem strange to declare an upstart like FCoE the winner when established options like InfiniBand, conventional Fibre Channel, 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. The few that really 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.
So Who Buys FCoE?
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!
Update: Storagebod points out that FCoE might see its first application in inter-switch links and other similar storage network infrastructure connections. And Chris Mellor at The Register points out that SAS is already displacing FC as an internal drive interconnect.