Terremark is offering enterprises a new private cloud storage service that includes the option to burst into a public cloud to handle big spikes in traffic.

The private offering, introduced yesterday, should appeal to customers in industries like financial services or government agencies that are interested in a cloud service but aren't comfortable with the shared approach, said Ellen Rubin, vice president of cloud products for Terremark, a subsidiary of Verizon.

The private cloud service is hosted at Terremark's facilities but gives users dedicated computing and storage. Customers will get some advantages of the cloud, like self service.

They also lose one benefit of the public cloud - easy scaling to accommodate for bursts in traffic. However, Terremark can quickly add capacity for customers, Rubin said. Also, users have the option to burst into public clouds, including Terremark's or others, like Amazon Web Services.

She said that customers may want such a hybrid environment for reasons beyond accommodating spikes in traffic. For instance, an operator of an e-commerce site might like to store their data in the private cloud but run the compute work in the public cloud. Some customers might also like to do development work in the public environment but run their application on the private cloud when they take their service public.

The connection with the public cloud also could appeal to customers that want to start out using the cloud in a private environment but transition to the public cloud once they gain experience. "For some customers, it's an adoption process," she said.

With its public cloud offering, Terremark competes directly with Amazon, which is thought to dwarf other providers in the market. But there's a reason that enterprises choose Terremark, said Rubin. "The reason they pick our cloud rather than EC2 is they really like the enterprise architecture we've built and the transparency we provide," she said. "What we've built is close to what they would build themselves." EC2 is Amazon's compute cloud offering.

Terremark's cloud is built on the VMware hypervisor and has technology from Cisco, Citrix and other vendors enterprises already work with, she said. Terremark invites customers to visit its data centres to ensure they meet a customer's compliance rules and offers professional services, Rubin said.

Most public cloud providers as well as a number of software providers offer products and services to help customers tie their public and private clouds together. Many analysts say that in the future most businesses that turn to the cloud will use a hybrid approach.