Ask any IT professional what they dread most, and they’ll likely tell you that it’s change. Specifically, the act of putting a new application into production: There’s simply no way to know what will happen.

Companies spend a tremendous amount of time and money in staging environments, trying to see whether or not their new code will work. Only the largest banks and utilities have the resources to completely replicate the production systems, and none can truly simulate the real world.

Jonah Paransky, VP of marketing for testing-sandbox startup StackSafe, says that roughly 43 percent of IT problems can be traced back to lack of pre-production testing. “Over half of the changes we see in our research never end up being tested against the end-to-end IT service.” StackSafe tackles the problem by copying an entire application into a virtual appliance, letting IT change it, and testing the result.

Virtualization is an important enabler for pre-production testing. IT has longed for a sandbox in which to let new applications play, but doing so in the physical world has been too costly. Increasingly, however, IT doesn’t have a choice: Best practice frameworks like the IT Infrastructure Library (ITIL) include processes for testing, and certain industries, such as power utilities, require that IT changes are tested and logged.

Server consolidation and disaster recovery firm Platespin also provides tools for sucking physical machines into the virtual world, but Paransky insists that StackSafe’s focus is different: In addition to creating a virtual clone of a production application, it offers a suite of testing tools to quickly see whether the clone is broken.

Easier pre-production testing couldn’t come at a better time. Because virtualization makes it trivial to create a new machine, IT administrators face a flood of newly minted virtual servers they have to manage. “Now that it’s almost no work to deploy new servers, the first thing that happens to new virtualized environments is an incredible growth in server sprawl,” said Paransky.

Sandboxing approaches like StackSafe have an important limitation, however. In order to insulate the real world from the servers being tested, the sandbox is completely cut off from surrounding systems. Otherwise, testing the sandboxed servers would have real-world consequences, like buying a ticket or selling shares. “Even if you could virtualize much of a production environment,” said Paransky, “there may be components, like SOA, that can never be pulled into that virtualized environment.”

Consequently, pre-production testing on the distributed Internet becomes increasingly difficult — you can’t put a copy of the Internet into your sandbox in order to test it. Which is a challenge firms like StackSafe still have to tackle if they’re going to improve the reliability of tomorrow’s applications outside of the traditional enterprise data center.