With HP's blade announcement and Sun's upcoming one it seems to me that, and no doubt lots of others, that blade servers could proliferate just like rack-mount servers have. It would make sense, when you have a chassis full of blades, meaning a hundred or more in a rack, that you save on host bus adapter (HBA) count and Fibre CHannel (FC) cable by having the chassis connect to the SAN fabric instead of each individual blade.

That way you could have one FC port for the whole chassis and one cable running to a director. Collectively a chassis' worth of blades could easily swamp a 4gig FC connection. This is especially so if the blades run VMware, in other words, have multiple virtual servers executing on them, increasing SAN traffic further. Well, 10gig FC is being used for inter-switch links. That's because the traffic levels need it and the lack of backward compatibility to installed 1 and 2gig FC doesn't matter.

Connecting a blade chassis to a SAN fabric could provide another application where 10gig FC is better suited than 4gig FC. In fact what we could end up with is a FC switch blade in a chassis. All the server blades can communicate to it and there is a 10gig ISL to the nearest SAN fabric entity outside the chassis.

Qlogic has its QMH2462, a 4Gbit/s Fibre Channel HBA for the HP BladeSystem c-Class. Emulex has also its LightPulse 4Gbit/s LPe1105 Dual Channel Host Bus Adapter (HBA) to enable SAN connectivity for the new HP BladeSystem c-Class. Qlogic also has a blade switch product. Connecting the bladed servers to such an in-chassis switch would require some kind of chassis fabric. Emulex' InSpeed technology could be a good fit here.

An IDC report quoted by Qlogic states: ""The addition of several new bladed server platforms from leading server vendors such as HP, Dell, Sun, and Intel promises to greatly expand the market opportunity in 2005. In addition, IDC expects McDATA to begin reselling its version of the QLogic switch, further driving expansion."

That was in August, 2005. Ten months on we can discern the bladed server chassis and bladed FC switch scenario beginning to take shape.

By 2009, the report estimated that blade server embedded switches would be rapidly approaching fixed port switches in terms of factory revenue ($309 million) and would be the largest Fibre Channel switch market in terms of ports shipped.

It might appear that there is not that much difference between 8 gig FC and 10 gig FC. But 10 gig has 25 percent more bandwidth. Double that up where needed and it offers 20Gbit/s as against 16Gbit/sec. The advantage is there and it is real.

It appears then, that are seeing the beginning of a transition to bladed servers in data centres dragging along a transition to bladed fabric switches and also, in my estimation, a transition to 10gig FC in its wake.