Half or more of the computing appliance vendors I’ve looked into follow very similar hardware strategies: They use mainly standard parts; they include uncommon but off-the-shelf networking (and sometimes encryption) accelerators; and they of course optimize the mix of those parts and general hardware architecture as well. (EDIT: I actually gave names to three strategies — even if they were just “Type 0″, “Type 1″, and “Type 2″ — in this overview of data warehouse appliance vendors. And in another post I considered arguments about whether one would want a data warehouse appliance at all.) Examples I’ve posted about recently include – and I quote the forthcoming column – “DATallegro and Teradata (data warehousing), Cast Iron Systems (data integration), Barracuda Networks (security/antispam), Blue Coat Systems (networking), and Juniper (security and networking).” (ANOTHER EDIT: But I think DATAllegro’s strategy has changed.)

By way of contrast, there’s also a group whose stance is more along “hardware/schmardware” lines. Sendio and Proofpoint (in most cases) don’t really do anything special at all in their boxes; what’s more, Proofpoint actually has significant software-only deployments over VMware’s virtualization layer. Kognitio and Greenplum think their software-only data warehouse offerings are appliance-equivalents too; indeed, Greenplum’s software is sold mainly bundled with Sun hardware (to the extent it’s sold at all), and Kognitio is hinting at an appliance-like offering for competitive reasons as well. Check Point Software plays both sides of the field; it offers its own kind of “virtual appliance,” but also gets many of its sales through appliance vendors. Its most interesting such partner, if not its biggest, is Crossbeam Systems, which in my opinion may very well represent the future of appliance technology.

• They use pretty generic computer parts. The biggest exceptions are specialized but still off-the-shelf cards for networking (fail-to-wire capability) and encryption. They think – as do I – that this is pretty typical for appliance manufacturers. However, different appliance vendors in the same market differ greatly in the mix of parts they use. (This is also true in data warehouse appliances.)
• They wrote their own OS. With fewer services than general operating systems, it’s inherently more secure (they fondly and credibly believe).
• They think there’s a general trend for specialized appliances to merge into more general ones. In the security/networking space, I’ve seen this too, but I don’t know whether the point has broader applicability.*
• Their maintenance fees as a percentage of purchase price are a lot lower than those typical for packaged software.

*But then, the vast majority of enterprise computing appliances are in the security/networking space. Data warehouse appliances are probably the biggest exception, at least if we define “appliance” loosely enough to include Teradata.