Linux: Ideal VM Base?

As for exactly what should be at the core of the virtualized software appliance, expect a lot of debate about whether a general-purpose OS or a "just-enough" OS is right, Marshall says. He argues that his just-enough approach, or jeOS (pronounced juice), makes sense for footprint and security reasons, for starters. "A general-purpose OS has to have everything there, just in case," he says. "It creates security and maintenance work."

RPath's JeOS approach uses a small slice of Linux as the base operating system for the software virtual appliance. Not a full version of Linux, but just the code needed to deliver and handle the software on the appliance. In a blog post that describes his argument for jeOS, Marshall argues that you should think of it not as an operating system but as a "packaging architecture"—free of the "dependency hell" that maintenance of general-purpose operating systems forces upon enterprise IT groups. Or, as he puts it plainly in another blog post: "Maintenance doesn't have to suck."

With a software appliance that uses the jeOS approach, the customer loses a little bit of flexibility, he says, but gains the advantage of avoiding hundreds of security and maintenance patches and updates to the general-purpose OS.

Guess who this vision impacts in the end? Yes, Microsoft, whose general-purpose OS you are probably running on your servers today, unless you have already moved to Linux.

But rPath's biggest direct competitor is the status quo, Marshall says. In other words, it will not succeed if the software vendors decide to skip the software appliance route and instead certify all those various hypervisors and deliver software in the traditional way. Of course, Marshall believes that choice makes little sense.

Successful SaaS vendors have already learned the lesson regarding lowering the cost of certifying and supporting the product on a slew of platforms, Marshall says. "Marc Benioff (CEO of Salesforce.com) is laughing all the way to the bank," Marshall says. "He certifies against one thing: his infrastructure." That means he spends between 8 percent and 9 percent of revenue on R&D, whereas most software vendors spend between 15 percent and 18 percent, Marshall says.

But rPath faces other rivals as well, Forrester's Staten notes: "There will soon be appliance toolkits from VMware, Red Hat and others," he says. "This will breed differentiation which will make it anyone's market to win. They (rPath) will have to be open, flexible, quick to market with new capabilities and incredibly responsive to their customer's needs." Toolkits, along these lines for enterprise customers, not just ISVs, will also arrive, though more slowly, and that market could be vastly bigger, Staten believes.

"We're making a big, long-term bet on a shift in the industry," Marshall says.

© 2009 CXO Media Inc.