Amazon has rolled out a persistent storage feature for its EC2 Elastic Compute Cloud, which should allow developers to use its hosted computing services for a much broader range of applications.

The feature, called Elastic Block Store, allows developers to create a storage volume of between 1G byte and 1T byte and attach it to "instances" of applications running in Amazon's cloud. Developers can then detach the storage volume and use it later for other application instances and back it up to Amazon's S3 storage service if they need more durability.

Without EBS, the storage volume is tied to a particular instance and the data lost when the job is terminated, Amazon said. EBS had been in closed beta testing for several months and was made widely available Thursday.

Right Scale, a company that provides tools and services for EC2 users, described EBS as "a Storage Area Network in the cloud." It said it will open EC2 to new usage scenarios, including allowing developers to take traditional relational database applications and move them to the Amazon cloud.

"What does EBS enable? In short: traditional processing on large datasets and reliable storage for many servers," Right Scale said in a blog posting.

Besides database applications, Amazon said EBS is suitable for "many other applications that require running a file system or access to raw block-level storage." It said multiple storage volumes can be attached to the same application instance, and developers can create "point in time snapshots" of volumes if they are backed up to S3.

EBS is priced at US$0.10 per allocated gigabyte per month, plus $0.10 per 1 million I/O requests made to a volume. So, a 100G-byte Web site database averaging 100 I/O requests per second would cost $36 per month, Amazon said.

The company has been working hard to attract more businesses to its cloud services, but recent outages haven't helped its cause. The S3 storage service was down for several hours last month, for example, which left some customers that depend on the service stranded.

The IDG News Service is a Network World affiliate.