Customers can provision a single volume starting at 1 Gbyte and expand up to 1 Tbyte. Multiple volumes can be connected to the company's Cloud Servers. Note that while volumes can be provisioned as a single gigabyte, customers must purchase the storage in blocks of 100 Gbytes. As mentioned, customers can choose between traditional disk and higher-performance SSDs. The pricing difference between the two is stark: Spinning disk starts at 15 cents per gigabyte, while SSD is 70 cents per gigabyte. The company says that unlike some competitors, such as Amazon, there are no additional charges based on IOPS. Snapshots can be stored on the Cloud Files service for10 cents per gigabyte per month.
While Rackspace touts its SSD option, Amazon also provides a high-performance storage option, though without the use of SSDs. Amazon's Elastic Block Store (EBS) service lets customers provision two types of volumes: standard and provisioned IOPS. In the provisioned IOPS option, the customer sets an IOPS rate for the volume. Amazon says it can support up to 1,000 IOPS per provisioned volume. Rackspace did not specify the IOPS performance of its SSD tier.
Rackspace's new service is built on top of OpenStack's Cinder APIs. OpenStack is an open-source platform for building public and private cloud services, with automation and orchestration controls for compute, storage and networking. Originally conceived by RackSpace and NASA, the OpenStack code base is now overseen by the OpenStack Foundation.
By building on OpenStack, "customers aren't locked in to a particular vendor," says John Engates, CTO of Rackspace. "If they decide to go to another OpenStack cloud, whether a private cloud or competitor's cloud, if they adhere to Cinder APIs, they have no switching costs because the product is provisioned the same across clouds."
Engates said the new service's most prominent competitor is Amazon's EBS, but the market is full of providers offering similar products. InformationWeek recently published an IaaS buyer's guide that profiles nine vendors, including Amazon, GoGrid, Google and Terremark. The guide provides a detailed breakdown of services. Many of the vendors profiled in the buyer's guide offer block storage, with prices ranging from 10 cents to 80 cents per gigabyte per month.
Rackspace says the Cloud Block Storage service is available immediately in its two U.S. data centers and its London-based data center.