Blades
I have seen many commercials produced by IBM about “Blade” servers but I never knew what made them different from traditional rack mounted server systems. When I came across this article on the Internet, I decided that it would be a great opportunity to find out more about blades.
A blade computer system has two major components: the blade and a rack type enclosure (either called a razor or a chassis). So far this sounds like a typical rack mount setup, but the details are what separate a blades from a traditional server. “A blade resembles an ordinary PC add-in card. In this case, however, the card is the computer. A typical blade features one or two processors, memory, storage—everything you would find inside a typical standalone server, minus the power supply, fan, network cables and other standard support components.” The components which were omitted in the blade are implemented by the blade chassis. The blades share the resources of the chassis including a high speed bus system which is used to connect the blades. The blades are not incredible computers individually with processors ranging from Pentium III to Xeon, but when connected over a high speed bus, they form a single computing resource which is both economical and easier to maintain than other supercomputers.
Because much of the hardware of a blade is shared through the chassis, blades can be packed much more densely than other server technologies. “Woodlands, Texas-based blade-maker RLX Technologies, for example, can wedge 24 blades in a 3U, which adds up to 336 independent servers in a single 42U rack with as much as 40 terabytes of storage and 336GB of memory.” That is a lot of power in a small space. Another advantage of hardware sharing through the chassis is the ability to “hot-swap” a blade should it fail.
Blades are an emerging technology and standards have not been developed for the interface between the blade and the chassis. Each manufacturer (IBM, HP, Dell, Sun) have their own proprietary way of connecting the blade with the chassis. This makes it impossible to use an HP blade in a Dell chassis. This vendor specific lock may slow adoption of blades. I think once standards are formulated, blade computing will be more accepted and really take off.
References:
CIO Magazine, 3-15-2003, “Servers on the Edge - Blades promise efficiency and cost savings”, John Edwards.