IBM has emerged as the leader in the blade server market - hardly surprising in some ways since the concept of a computer-on-a-blade is not new to Big Blue - some five percent ahead of nearest rival HP. For the enterprise computing veteran, computers that slot into chassis-providing services such as I/O, communications and power have been its stock in trade for decades.

Core hardware
The company took its time entering the blade server market, which was already well under way by the time IBM made the product available in 2003. Its systems were then and are now based around a central chassis, made in two formats, 8-slot and 14-slot, with the former aimed at telcos. This chassis, jointly developed with Intel and dubbed BladeCenter, is at the core of IBM's blade server strategy, since everything else in the system is based on it.

A typical IBM blade contains a pair of Xeons, up to 16GB of memory, a pair of Gigabit Ethernet controllers and I/O expansion capabilities for Fibre Channel, Ethernet and Infiniband - although the company has just announced a 10Gbit Ethernet blade.

HP's approach with its BladeSystem is similar to IBM's - the two are locked in combat for the same customers' wallets - but it does have a slightly different tune to play. It can additionally offer Itanium-based blades, which run HP-UX, and these go head to head-to-head with IBM Power-based blades, which are typically set up to run IBM's AIX or Linux. there's little evidence however that the market has taken to buying Itanium blade servers en masse.

Others take a slightly different route to blade design. Third-slot player Fujitsu Siemens sees server blades as CPU plus RAM and nothing else. Its Egenera BladeFrame has extra hardware and software to assign disks, a network connection, operating system, middleware and application software to the raw server blades. In effect a virtual server exists as a configuration file on a BladeFrame disk. When a new server is needed, this virtual server is instantiated on a real server blade.

The sweet sport for the two leaders -- who between them own 75 percent of the market -- is the two-way blade. IBM reckons most customers buy twin-Xeon blades, eschewing the power savings to be had from the low-voltage part and opting for performance. IBM will sell any flavour of Xeon, including the low-power version, up to four per blade. It also sells AMD Opteron-based blades, as does HP.

IBM has made much of its cooling technology. With high-powered processors tightly packed on a blade in close proximity to other heat-producing components, blade makers need to walk the tightrope of offering their customers more power, and allowing them to save floor space in their data centres, while bowing to the laws of thermodynamics. IBM uses a technique known as vectored cooling, which it borrows from its mainframe designers. Big Blue reckons that the technology optimises the path of cooled air flow through the system, allowing IBM to use fewer fans while maximising system density.

Open standards
Arguments raged about standards in the early days of blade servers, and whether vendors should jointly develop a common hardware standard. This would, for example, allow blades from HP to plug into a BladeCenter. No vendor has taken up that challenge, each one claiming that its chassis was a major element of its product development strategy, and allowed it to differentiate its products.
IBM has though initiated a first in the blade server market, namely to open up its BladeCenter hardware specification to third parties. The aim of the move, which IBM made in concert with Intel, is to encourage hardware vendors to develop hardware add-ons, such as networking switches, blade adaptor cards, and appliance and communications blades - provided they sign a seven-page licensing agreement, which grants them the rights to license the specifications for certain types of products. The opened specifications include guidelines and tips and tricks for building blade components.

Only some of the blade specifications are in the specification, which prevent third parties from cloning the blades themselves and cannibalising IBM's lucrative market; customers also still need to go to IBM or Intel for the chassis and management modules. HP hasn't followed suit but does share specifications with selected hardware vendors under non-disclosure agreements.
IBM's is not a truly open standard. Gartner analyst John Enck was reported as saying that, "While Intel and IBM are trying to create a de-facto standard, this is not truly an industry standard. Blade technology remains highly proprietary and will remain so for many years."

Management is key
Key to all these systems though is the ability to manage them remotely. Once they tucked away inside the chassis, you're unlikely ever to see them again unless they either go wrong or are superseded. IBM punts its Director product for hardware management, which it describes as "an open, integrated suite of software tools that provide a consistent, single point of management and automation." Among the features it offers are predictive failure analysis, health monitoring, remote supervision, and what IBM calls light path diagnostics -- you follow a path of lit LEDs towards the problem area.

HP's BladeSystem Management Suite, bundled in with each blade, offers similar capabilities, though without the light path.

So IBM's approach is unique only in that it offers to open up a part of its blade technology. It remains the leader of a market that grew 43 percent in the first quarter of 2006 compared to the same period in 2005. Blades represent five per cent of all server sales.

But IBM appears to be doing enough to stay ahead of HP - maybe all those years of big iron experience did help it sell into a rapidly re-centralising enterprise customer base after all.