The infrastructure requirements of a cloud application can fluctuate a great deal, particularly when it comes to performance. On Monday, Microsoft Corp. introduced an instance family for Azure specifically designed to deal with such usage changes.

The new B-Series virtual machines can operate at a wide range of performance levels. When the baseline processing power available to an instance is not fully utilized, it racks up credits that are saved up for times when additional horsepower is needed. The accumulated computational resources enable the workload running inside to meet sudden usage spikes without incurring extra costs.

B-Series instances come in six different sizes. The cheapest configuration offers a single virtual processor for a starting price of 1.2 cents per hour, while the most expensive packs eight virtual processors and is available from 37.6 cents per hour.

Microsoft is not the first cloud provider to have implemented the concept of processor credits. Amazon Web Services Inc., the market leader, has offered a similar capability with its T2 instances since 2014. Google Inc. likewise provides virtual machines that support the ability to carry over unused performance.

These virtual machines are mainly geared toward development environments and relatively small applications. Such workloads often can’t be efficiently accommodated by a traditional cloud instance, since pricing is usually based on the maximum performance.

Larger applications have more sophisticated ways of meeting usage spikes. On Azure, a recently introduced service provides the ability to automatically create extra instances when the need arises. They’re billed by the second and can be simply shut down when demand returns to normal.

Microsoft’s Azure Functions offering provides an even more fine-grained billing model. The service enables customers to run code on-demand in response to certain events and pay only for the hardware resources used up in the process. As is the case with the new B-Series, other top providers such as AWS offer their own competing versions.

Image: Microsoft