Did you think the market for servers was neatly carved into four main pieces, with HP/Compaq occupying one chunk, IBM another, Dell the third, and the rest of the vendors, from Fujitsu to Evesham filling the gaps in between? Think again.

Stratus Technologies, which has just launched a new range of highly fault-tolerant servers, occupies one very significant chunk of the market yet remains one of those companies that many thought had disappeared in the big shake-out of 2000-01. Instead, it's just been a bit quiet. But that has all just changed.

Founded in 1980, the company has though gone through a bit of an evolutionary bottleneck in recent years, having been acquired in 1998 by Ascend Communications, which was itself bought by Lucent in one of the big buy-outs before the bubble burst. A split into enterprise and telco business companies was followed by a reunification last year, leaving the company looking pretty much as it did in 1998.

The company has always been in the fault-tolerant server business but two initiatives delineate the past from the present. First, it is selling Windows computers where previously its own VOS operating system was its core software platform, and the one on which its reputation was built. While the advantage VOS gave it of having control over more of the variables may have been a good thing, servers are now becoming commodities. This pulls prices down and makes the price of custom applications on a proprietary platform prohibitive, resulting in economic pressure to shift away from the old strategies.

The other key initiative is that Stratus has started to shout about what it does. For example, sitting in the room where it launched its new servers this month were customers from major financial institutions. These included NatWest, Citigroup, Merrill Lynch and American Express, among a host of other household names - including my local police force. The atmosphere between the Stratus executives and its customers was clubby - these people have been doing business together for a considerable time, and Stratus clearly has got to know them well. It even treated them to dinner.

Yet it felt the need to announce quite recently that it was offering $100,000 to any company whose Stratus servers suffered unplanned downtime. No-one has so far needed to accept that offer. And the fact that it was launching the servers publicly at all was something of a first.

Where previously it sold the benefits of its servers directly to individual vertical markets, such as finance, public services and utilities - areas where either lives or very large amounts of money, or both, may be at risk if a server ever goes down - now it's selling through channels to a more general or horizontal audience.

Stratus has even started selling on price, which it has rarely if ever done before: one presentation speaks of its servers being one-third less expensive than a Unix cluster, one-fifth of an HP Non-Stop server - and one-fiftieth the downtime of an Intel-based cluster. It has described its new Intel-based products as 'highly affordable'.

What does it all mean? It's simply that the whole idea of zero downtime has become mainstream. Ecommerce and other activities that absolutely must not stop - not least because regulatory compliance if not good governance now mandates mainframe levels of resilience and business continuity - are spread across the commercial spectrum, not confined to those tasked with keeping the water, electricity and money flowing.

As IDC's Avneesh Saxena says in a Stratus-sponsored report, "Given the current integrated computing environment, IDC expects fault tolerant servers to increasingly appear in front of customers, as well as to provide the first line of IT processing defence inside a data centre." The report concludes, "The x86-based ftServer systems strengthen Stratus' overall value proposition in the fault-tolerant market space."

And in a second report, IDC's Lloyd Cohen says, "the number of applications that are considered to be mission-critical will expand. Stratus is in an ideal position to provide the changing requirements of the IT infrastructure. To date, Stratus’ success in these [lower] server price bands has gone largely unnoticed by the non-fault-tolerant providers, but if the company is able to continue to grow its business and its share year over year, this will most likely not be true in a few years’ time."

Bolstered by analysts' urgings and with the knowledge that to stand still in this barely-growing server market is to die, Stratus has ported its systems over to IA32 and started a marketing campaign -- albeit a muted one compared to those traditionally mounted by other server vendors -- in a bid to boost market share.

It will be intriguing to see what other products the company decides to bring to market, how big a premium it can continue to charge for its differentiator, and how players such as HP, IBM and Dell - who may be disrupted by Stratus' entry into their territory - respond.

Meanwhile, if you're in the market for non-stop servers, you might find Stratus in an accommodating mood.