Block-based cloud storage services provide logical management of storage volumes over a virtualized storage network, with a web-based service interface. Cloud-based mass storage services allow you to add a logical drive of a specific size and capacity to any cloud virtual machine. This cloud storage volume can only be accessed by the cloud VM using low-level hard drive access protocols. Cloud block storage must be provisioned prior to use. Depending on its performance objectives, for example, for use in databases or file systems, it can support a specific number of Input/Output Operations Per Second (IOPS). Most cloud providers adjust pricing based on the number of IOPS available for use with their block storage volumes.