Amazon just made life a little harder for old-line computer companies, by making a play for their data storage backup business.

The bookseller’s Amazon Web Services company has announced a service that will enable businesses to move their data to Amazon’s data centers more easily than before. The AWS Storage Gateway, as it is called, is software that customers install into their own computers to connect securely with Amazon’s storage cloud, and securely send to AWS copies of corporate data to encrypted files.

“We see it as a good on-ramp” to cloud computing, Alyssa Henry, general manager of AWS Storage Services, said in an interview. “This is a good way to pay for capacity only when you need it.” The product is aimed at large corporations, she said, though it is possible that resellers of computer services might offer it to the small and medium-size business market.

Amazon’s pitch is aimed at companies that are not yet comfortable with cloud computing, offering them a cost-effective way to back up their data and test new software applications without disturbing their existing computers.

Data storage backup is one of the less exciting, but nonetheless critical, areas in enterprise computing. Disasters from networking failures to bad software can cause data losses, and companies almost always keep one or more “mirrors” of their data. Doing so on site requires extra machines, and often extra talent to look after the machines.

As companies become more comfortable with cloud computing, Amazon hopes, they will think about moving existing operations into the AWS cloud-based storage and servers, even using AWS to build and run all of their software applications.

The move kicks up the competition between existing on-premises data storage companies and cloud service providers in several ways. For one thing, Ms. Henry said, this is the first time that Amazon has put its own software into companies. The software is called a virtual “appliance” because it carries out separate functions in customers’ hardware and offers customers information on their data inside Amazon’s cloud.

“A number of customers asked us for something like this,” Ms. Henry said. “It is an easy way for them to grow without expanding” equipment and personnel.

By going after backup storage, which does not have to be loaded in real time, AWS is avoiding a common criticism of the service, variations in the speed at which people can move information.

AWS also says the Storage Gateway was an easy way to pick up a little extra computing capacity off EC2, Amazon’s cloud-based servers offering, using the data that companies have already loaded into AWS.

The service meets storage and data recovery standards in regulated industries like banking and health care, Amazon said in a release. These businesses are are often wary of cloud computing.

AWS said the service would cost $125 a month for each gateway, after a 60-day free trial. The storage starts at 14 cents per gigabyte of data a month. By comparison, Hewlett-Packard’s entry-level disk-based data storage system, holding 3,000 gigabytes, lists online for a starting price of $1,899.

The announcement follows last week’s move by Amazon to offer a new online version of a NoSQL database. This product, a database that can be drawn on by potentially thousands of servers, is useful for companies already comfortable with cloud systems that want to run very large-scale projects like sales across the Internet.