A policy specifies a list of volumes and the order in which to attempt allocations. A policy can be assigned to a file, a file system, or a Storage Checkpoint created from a file system. When policies are assigned to objects in the file system, you must specify how the policy maps to both metadata and file data. For example, if a policy is assigned to a single file, the file system must know where to place both the file data and metadata. If no policies are specified, the file system places data randomly.