When big companies run out of space on one of their servers -- the electronic silos that house e-mail messages, documents and Web sites -- expensive computers automatically shift the information to another server with extra room. Many smaller companies wish their systems would work the same way but cannot afford the pricey routers.

But if Thieu Le, the founder and president of String Bean Software Inc., gets his way, corporate pack rats of all sizes will be able to store their electronic stuff for less. String Bean sells a modestly priced computer program that enables multiple servers to act as one. That's significant because data on an overcrowded server can spill over into the hard drive space of another server. Now companies buy extra space for individual servers by forecasting future storage needs. If someone makes a bad guess, the company is stuck with extra capacity on one server that another server cannot use.

"We're targeting the low end of the market, mostly companies with 250 employees or less," said Le, who also serves as chief technology officer.

But one of the world's biggest companies, Microsoft Corp., has also been a customer since February. The software company uses String Bean's software on the mini-networks that connect employees collaborating on projects. Those "work groups" usually have up to 50 people.

The program is useful for small businesses because the mail servers that handle e-mail traffic constantly need more space while the amount of data on servers dedicated to a company's Web site rarely grows, Le said. Using String Bean's software, a company can first fill up a Web site server before buying more hard drive space for its e-mail.

The company has spent most of the last year writing and testing the software, and it began selling a finished version in May. About 10 companies are using the software. They pay String Bean a $250 licensing fee for each computer hooked up to a network using the program. For companies using the software on more than 10 computers, the price is capped at $2,500.

Thieu Le, founder and president of String Bean Software, a Gaithersburg firm specializing in software that allows servers to unload excess capacity to servers with unused space.