Virtual machine storage policies are essential to virtual machine provisioning. The policies control which type of storage is provided for the virtual machine, how the virtual machine is placed within the storage, and which data services are offered for the virtual machine.
vSphere includes default storage policies. However, you can define and assign new policies.
You use the VM Storage Policies interface to create a storage policy. When you define the policy, you specify various storage requirements for applications that run on virtual machines. You can also use storage policies to request specific data services, such as caching or replication, for virtual disks.
You apply the storage policy when you create, clone, or migrate the virtual machine. After you apply the storage policy, the Storage Policy Based Management (SPBM) mechanism places the virtual machine in a matching datastore and, in certain storage environments, determines how the virtual machine storage objects are provisioned and allocated within the storage resource to guarantee the required level of service. The SPBM also enables requested data services for the virtual machine. vCenter Server monitors policy compliance and sends an alert if the virtual machine is in breach of the assigned storage policy.
See vSphere Storage for more information.