ARN

Review: Duelling blades

It has been a long, strange trip for RLX Technologies. A blade server pioneer, RLX has gone from promising startup to controversial innovator (it was the poster child for Transmeta's Crusoe chip in the server space) to pragmatic good citizen, content to toe the Intel party line. Along the way, the market it helped establish - high-density, low-voltage server devices for Web applications - became decidedly more crowded thanks to a surge of interest from various industry heavy hitters.

When it comes to Intel-based enterprise server platforms, nobody hits more heavily than Compaq. Just when it looked like the whole blade server experiment was running out of steam, Compaq unveiled its remarkably RLX-like ProLiant BL10e.

Compaq's entry had two effects: it legitimised the underlying technical premise that high density plus low power consumption is a good thing; and it forced RLX to seriously reconsider its Transmeta-only stance. RLX responded by fielding a compelling new Intel-based platform, the System 300ex, and was first to market with an 800MHz Server Blade solution. The race was on!

Getting down to business

We really wanted to construct an "apples to apples" comparison, but Compaq's inability to provide us with an 800MHz part by press time left us with no choice but to use its slower 700MHz Pentium III-based blade. The megahertz deficit showed: during testing with CSA Research's ASP Stress 3.0, which simulates a Microsoft ASP-based, three-tier Web application, the Compaq BL10e system took as much as 30 per cent longer to complete the same SQL Server transaction loop, depending on client workload.

We faced some challenges in designing a benchmark test for this review. Blade servers are, by their very nature, self-contained computing "appliances". As such, they place a number of restrictions on application design, including the need to accommodate load balancing. Many Web applications require modification before they can run seamlessly across a cluster of identical servers.

In our case, we needed to modify how we handled session identification, because the different instances of the IIS (Internet Information Server) often generated identical session IDs on both blades. It's this kind of hidden gotcha that can derail the otherwise seamless "scale-out"- scaling horizontally with more devices, as opposed to vertically via bigger and/or faster CPUs - message that has become the mantra du jour of the server blade community.

The aforementioned performance delta notwithstanding, the Compaq and RLX solutions are functionally quite similar. Both provide excellent blade density: 24 per 3U rack with RLX System 300ex and 20 per 3U rack with Compaq ProLiant BL10e. Both also provide cable aggregation options for the back of the chassis; RLX provides a high-density RJ21 connection whereas Compaq offers a choice of RJ21, RJ45 or an integrated four-port, gigabit-switched backbone.

Both blade solutions operate in what is essentially a "headless" fashion, with no keyboard, display, or mouse. Compaq does provide a rather bulky dongle that exposes these ports, as well as a pair of USB connectors, but that's where its advantages end. In virtually every other area, from ease-of-use to overall cost to deploy, the RLX solution comes out the clear winner.

Take blade management, for example: with the RLX solution, a single Control Tower blade in a single chassis can manage an entire data centre full of blades. Because the RLX Control Tower blade is essentially just another server blade with extra software, replacing it in a failure scenario is as simple as re-imaging another blade in the chassis. By contrast, every Compaq chassis requires a dedicated Interconnect Tray, and at $US2,000 a pop these can add up quickly, as can the software licences: $US119 per managed blade for the Compaq ProLiant Essentials Rapid Deployment pack compared with $US50 for the RLX Control Tower software.

Other smart ideas in the RLX box include a dedicated management NIC (network interface card) channel to isolate provisioning and imaging traffic; the Compaq BL10e requires all management traffic to flow over the public LAN connections. RLX also includes an external LED on the blade enclosure for the chassis and rack ID numbers, making it easier to identify a specific blade location.

However, Compaq engineers have some clever ideas of their own. For example, each blade in the BL10e sports its own diagnostic LED that can be triggered remotely - a real time saver when you're hunting through a data centre full of chassis.

Putting it in perspective

With superior price and performance and a host of intelligent design features, the RLX System 300ex is the platform to beat in the budding blade computing space. The entire RLX solution seems thoroughly well-rounded and oozes that kind of balanced feature set that can only come from a seasoned, third-generation product architecture.

Compaq's BL10e is a respectable first-generation attempt and benefits from the backing of Compaq's extensive service and support infrastructure.

Nevertheless, neither company can afford to rest on its laurels. Of great concern to both RLX and Compaq is arch-rival Dell's announcement that it will begin shipping its own server blade solution in the second half of 2002.