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Using fibre channel for storage networking

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If you think the idea that data centres would abandon Fibre Channel for converged Ethernet was pie-in-the-sky, you are in good company. Very few data centres now run solely on Ethernet—mostly new ones that were built with it—but Fibre Channel remains king, especially with the latest 16 Gbps version now available and 32 Gbps being discussed for 2014 delivery. 

What definitely is changing though, according to analysts and vendors alike, is the relationship between the front-end and backend networks. Increasingly this is leading to hybrid data centre fabrics, using the most appropriate technologies in each region, often with Fibre Channel over Ethernet (FCoE) as a key component. 

“Clearly, Fibre Channel is still the [storage] network of choice in data centres,” said Tony Lock, an analyst with Freeform Dynamics. “You’d probably go converged in a greenfield data centre, if your designers are happy with that, but for others it’s how do we get there, what are the training requirements, what’s the business need?” 

“We’ve always said the number one choice in the data centre for reliability, performance and stability is Fibre Channel, and we’ve been proved right,” said Simon Pamplin, Brocade’s UK & Ireland software engineering director. He added that automated tools for setup and diagnostics mean that, “storage networking is probably the easiest network to put together at a low level now.” 

“Hundred percent Ethernet fabric won’t take over any time soon,” said Daniel Bizo, a storage analyst with IDC Europe. He points out that greenfield data centre builds are rather less common in Europe than in the US, where many Ethernet storage developers are based, and added, “Fibre Channel is a pretty decent technology—it’s high speed and low overhead, so 8 Gbps Fibre Channel outperforms 10 Gbps Ethernet, and it is the safe path. You cannot guarantee peace of mind and an SLA on Ethernet.” 

Looking forward, the most likely option for Fibre Channel users is, therefore, faster Fibre Channel, said Jason Phippen, senior director EMEA at Emulex, which makes both Ethernet and Fibre Channel adapters. “There is a lot of 4 Gbps Fibre Channel out there, and a lot of people are still buying it,” he said. “We will see a significant transition away from 4 Gbps this year though—the price difference between 4 Gbps and 8 Gbps is not great now, plus a big driver is that OEMs will be end-of-lifing 4 Gbps, and a lot of next-generation servers will not support it.” 

He added, “I don’t believe Fibre Channel will disappear at all, especially for non-virtualised high performance and database environments. Organisations have a large investment not only in the hardware but in skills and management tools. And there are still new Fibre Channel networks going in; we’re seeing good growth there in Eastern Europe and emerging markets.” 

Of course, the next few years will also see a lot more Ethernet. Lock said that in surveys recently carried out by his company, 40% of respondents reported investments in 10 Gbps Ethernet, rising to 60% if you include those planning investments. A small number even have some 40 Gbps Ethernet in place. 

So where is that Ethernet going? Some of it is iSCSI, typically for specific projects and in organisations that don’t have a Fibre Channel investment, some is FCoE, mostly for fabric bridging—and a lot is to do with server virtualisation, where Ethernet fabrics are well suited to the growing need for inter-server traffic and the movement of virtual machines. 

The decision on which route to take will come down to skills, budget and how comfortable you are with the technologies. As ATA-over- Ethernet storage vendor Coraid’s marketing vice president John Gilmartin said, “The data centre is becoming very dynamic. Fibre Channel works well if you have a few servers connected, but as you get more servers and they’re moving around, Ethernet comes to the fore.” 

Emulex’s Phippen said that 10G Ethernet is out there and shipping with OEMs, although a lot of people bought converged Ethernet adapters as investment protection and are actually using them as NICs. “Where customers seem to have deployed FCoE is for the wire-once requirement—for example, if you have new blade servers on Ethernet and a legacy SAN,” he added. 

So, where some vendors initially pushed FCoE as a step along the way to an all-Ethernet fabric, it is instead emerging as the bridge between the SAN world and the new realm of server virtualisation, where 10 Gbps Ethernet is the simpler choice. Just like converged Ethernet, this approach removes the need for server HBAs—or some of them, at least—but it leaves the storage infrastructure where it is. And when you are a storage or IT manager trying to do more with less, and in a shorter time, that hybrid approach could be a very good thing. 

Bryan Betts is a UK-based journalist specialising in business and technology and a contributor to SearchStorage.co.UK.


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This was first published in September 2012

 

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