back to article Directing Fibre Channel storage traffic over Ethernet

Fibre Channel over Ethernet (FCoE) has a hard act to follow. Fibre Channel storage fabrics accomplish an amazing feat, making shared storage arrays equivalent to direct-attached disk drives to the many servers accessing them. When servers access data from directly attached disks, the data arrives fast and none is lost en route …


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Effing Coe!

And work well FC does too!

Strangely enough the big HBA players, like Qlogic, Emulex and the like are promoting both topologies without pressuring the channel towards FCoE. To be honest, FC is still their primary revenue stream and they are not going to do anything to quell that business flow at all.

Another issue is the [current] cost of 10GB and Converged switching equipment, it's still not "that cheap", whereas the cost of a capable 8 port enabled/16 port ready, 4GB/s FC switch is under the £2.5K mark with SFPs and cables.

The emerging technologies of Virtualised IO, like those very clever Xsigo directors is another factor that may be keeping the industry away from FCoE. Just connect your current FC Switch and iSCSI arrays to the Xsigo box, drag and drop the LUNs to the relevant [Virtual] Servers and ta-da!

The industry has been banging on about FCoE for some time now, I only ever see it being implemented in a green [new] installations, however those who have a reasonable sized investment in 4/8G FC will stick with what they have and/or perhaps look at the Virtual IO opposed to the fuss of mixed storage connectivity within their DC


FCoE Standards

T11′s FCoE standard, FC-BB-5, had its technical draft completed in October 2008, was submitted for publication in June 2009, and published May 2010. FC-BB-5 includes the FCoE Ethernet frame protocol, and the FIP protocol (required for multi-hop). Multi-hop FCoE has been a published standard for over one year, and has been available in final form for two years.

The only IEEE Ethernet standards required to support FCoE traffic are IEEE 802.3-2008 PAUSE and IEEE 802.1Qbb Priority Flow Control. IEEE 802.3-2008 is standard, IEEE 802.1Qbb is complete and was submitted for publication a year ago (July 2010).

One other Data Center Bridging standard, IEEE 802.1Qaz, which includes Enhanced Transmission Selection (ETS) and Data Center Bridging eXchange (DCBX), is complete and was submitted for publication in November 2010.

IETF TRILL is not part of the IEEE, is not part of of the IEEE's Data Center Bridging Task Group, and is not required for FCoE or multi-hop FCoE.



The article doesn't mention the elephant in the corner: Interop.

The different FCoE solutions are all vendor-specific. If you install a Brocade FCoE SAN, good luck with plugging it into your Cisco infrastructure.

Borrowing words from Steve Jobs:

FCoE is a big bag of hurt.

Until everything works seamlessly all of the time, I don't see any broad based installations.


Fiber people are used to that

Try using any SFP in another vendor's system, or even an older version in newer kit. Ethernet people are routinely shocked that anyone would still pay for such heavily locked-down equipment.

That's why I see iSCSI a lot more than FCoE, it is NOT quite as "just works" and "plug-and-play", but it's also not as locked into one vendor. Burned once, twice shy. Once there is an actual FCoE standard with cross-industry interop, it will probably surpass iSCSI because it's technically superior, but until then hardly anyone is going to be willing to trust all of their eggs in one vendor's basket.

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