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Virtualization and Linux can be a match made in heaven, which is why enterprise Linux heavyweights Red Hat and Novell are pushing so hard to make support for virtualization a highlight of their respective mainstream Linux operating systems.

Also recognizing this potential—but pursuing a markedly different tack toward realizing it—is rPath, a company that offers IT organizations and the ISVs that serve them a clever new means of getting the most out of this technology tandem.

Virtualization products—such as those from VMware, Microsoft and the open-source Xen project—let administrators boost utilization and sidestep software conflicts by deploying applications in customized operating system environments.

Linux—with its free licensing, ready malleability and broad server application support—is particularly well-suited for hosting applications in these sorts of environments.

However, despite the amenability of Linux to stripped-down, application-optimized implementations, the task of assembling and maintaining a custom Linux operating system is complex.

Indeed, it’s a task that only the most Linux-savvy development operations likely are willing to take on.

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rPath has attempted to split the difference between the roll-your-own and one-size-fits-all Linux approaches by building, maintaining and supporting a distribution of its own. The result is rPath Linux, and ISVs can marry their wares to it to create ready-to-deploy software appliances.

rPath also offers a tool set called rBuilder for surrounding applications with required components; for keeping these components up-to-date and in sync with users’ own code and customizations; and for providing customer-facing niceties, such as a simple Web interface, for conducting basic administration tasks—in essence, creating a customized Linux distro.

rBuilder can output customized Linux distributions as VMware images, among other formats, making these software appliances a natural and easy fit for virtualized deployments.

Version 2.0 of rBuilder was released in August at the LinuxWorld Conference & Expo in San Francisco.

Weighing the rPath Approach

The rPath model leaves ISVs free to focus on their applications and the operating system tweaks that will cast their wares in the best light. What’s more, rPath’s approach should make support and maintenance easier for ISVs by eliminating most of the customer-introduced variability that’s inherent in general-purpose operating system deployments and that can potentially interfere with an application’s smooth operation.

Meanwhile, the rPath model leaves enterprise IT administrators free to focus on providing a virtual application environment that is well-managed and that takes full advantage of the hardware resources available.

They can then simply drop rPath software appliances into the virtual containers they’ve created, leaving others to worry about tweaking Linux in a way that will work best with the applications being offered.

However, while rPath offers to its downstream customers and users what may be the fastest available route to building a custom Linux distribution, it is a relative newcomer among Linux distributors. The company will have to prove itself to customers and users as a dependable source of updates, support and technology integration in the fast-moving open-source space.

Getting it

IT administrators most likely will come into contact with rPath through one of the products delivered by rPath’s ISV customers. Ingres, for example, announced at LinuxWorld a database appliance built with rPath’s distribution and tools, and Digium has announced that it’s working with rPath on an Asterisk-based appliance.

There are several other fairly mature rPath software appliances available for download from

These include SugarCRM and MediaWiki appliances, both of which we tested and which show off rPath’s Web administration interface.

During tests we used this Web interface to set up options such as software update schedules and administrator notifications. We also tried out a fledgling Linux distribution from The Foresight Linux Project called Foresight Desktop Linux that’s based on rPath’s Linux distribution and associated tools.

rBuilder is available in two flavors. rBuilder Online is free to use, with the provision that the appliances created online remain free for anyone to download.

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For ISVs and customers who wish to control the distribution of their appliances, rBuilder is available in a self-hosted appliance version that costs $5,000 and up, depending on the number of users and deployed CPU sockets.

Appliances built at come with mailing list hosting and the option of offering appliances for download as x86 or x86-64 installer iso images, complete with Red Hat’s very good Anaconda installer application.

rBuilder also outputs appliances directly to raw disk image or VMware image formats.

Advanced Technologies Analyst Jason Brooks can be reached at “

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