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FC Me

Yo happy reader,

Been up to my ears post–IDF but, a veritable plethora of storage–related announcements simply will not go away. So, let’s start whacking those storage moles by looking at FCoE, a new kid on the storage block.Fibre Channel over Ethernet, a.k.a. FCoE. We all know about Fibre Channel, that block–level SAN or Storage Area Network protocol that allows multiple user access files almost as if they were local. Block–level means that you can read and, more importantly, write, to the smallest logical quanta of a file. In comparison, NAS or Network–Attached Storage only allows whole file–level writes. In Ye Olden Days, a “file server” was the functional equivalent of a modern NAS. Because of the nature of the protocols and the nature of the interconnection infrastructure or “fabric,” SANs are fast in comparison to NAS devices.

OK so, what’s with FCoE? Old skool FC ran over copper for very short distances and, for moderate distances, over glass fibre. FCoE is cool for several reasons…first, it maps then wraps FC protocols in IP packets, which means the interconnection infrastructure can now be any IP network. Lots of caveats there but, I’ll get back to that in a moment. Another benny is that, because FCoE runs over IP networks, you can not only use most of an existing physical ethernet layer but, you can also use many of your ethernet brain cells. Your generic “IT” gals, instead of the special “storage” geeks, can now deal with a unified network of files and blocks (cue the Heavenly Hosts).

Unfortunately, this is somewhat like Dr. Venkman’s “…disaster of biblical proportions,” dogs and cats living together, that sort of thing since we all know that most companies are roughly organized into armed camps where each camp, er, department, will fight tooth and nail (to continue this clawed mammal metaphor) to protect their fiefdom’s status and budget. Welly well, trying to shrink or reallocate any departmental resource, whether human or hardware, usually isn’t an easy thing.

Another caveat is just what kind of IP network are we talking here? That would be “lossless ethernet.” Pardon? Lossless ethernet? That’s an oxymoron! By definition, ethernet is a lossy as the postal service. It’s a “best effort” approach and, if a packet or twelve goes missing then, oh well, send it again and cross you fingers. Now, as IT protocols grow from baby standards that can barely walk to robust, powerful protocols that sweep the sissies aside, they usually gain QoS or Quality of Service–related features. USB, once the laughing stock of the local bus crowd, now actually has some meat on its bones in the 3.0 implementation. Same goes for 6Gb/s SAS and now, for ethernet. I’ll get into 6Gb/s SAS (hey, I don’t make up these names, I just reports ’em as I sees ’em) and SuperSpeed USB in a future post but, when 10 Gigabit ethernet came along a few years ago, it included new features to guarantee delivery. FCoE requires lossless 10GigE since, its Fibre Channel antecedents are lossless as you would expect from a storage protocol.

Another benny is that FCoE takes Fibre Channel from a local protocol to, in theory at least, a Metro and maybe even a Wide Area Network (MAN & WAN) protocol. Latency, the tiny David that killed many a networking Goliath, would need to be very small indeed to allow FCoE to work over extended lengths. Despite the hurdles, I’m guessing it will come to pass real soon but we are talking big budget, data center kinda stuff here, not your “I’ve got a couple of networked edit bays here…” kinda thing.

We’re already starting to see FCoE implementation out in the marketplace. EMC expanded its lineup of FCoE technology with the introduction of the EMC Connectrix MP-8000B switch. It “…allows both local area network (LAN) and storage traffic to travel on a single 10 Gigabit Ethernet link, eliminating the need for separate storage area network (SAN) and LAN adapters and cables. Reducing the number of adapters and simplifying cabling helps lower equipment acquisition costs as well as the operational costs associated with server power consumption and cooling. The FCoE protocol preserves Fibre Channel constructs and services, allowing the Connectrix MP-8000B to seamlessly integrate with existing Fibre Channel SANs, management processes, and workflows, offering a smooth migration path for existing SAN customers.” What he said. Network filer king NetApp was the first out of the gate and many more will follow.

The way things are going, ethernet will become the One Protocol That Rules Them All. Not only will it not die peacefully, but it seems to inexorably add new functionality like Anthony Stewart Head’s Baltazar on Dr. Who. It added features that are useful, borrowing protocols that already have some prior Deep Thought built in. Fibre Channel did the same thing back in the day, stealing its channel coding cuz it was already proven. 6Gb/s SAS stole some of InfiniBand’s PHY features along with that same 8b/10b coding and now, ethernet pilfers storage protocols, adding one more, er, notch to it’s handle?

Yikes! What with all this bloggin’ about buses and protocols and whatnot, I’m, as Amelia Bedelia repeatedly says, “…plum tuckered out!” Plus, my similes and metaphors are becoming dangerously obtuse so, time to go. Hope you liked this SANnish rant. Drop a comment, yay or nay and, continue to geek!

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