After you define a VM storage policy, you can apply it to a virtual machine. You apply the storage policy when provisioning the virtual machine or configuring its virtual disks. Depending on its type and configuration, the policy might serve different purposes. It can select the most appropriate datastore for the virtual machine and enforce the required level of service, or it can enable specific data services for the virtual machine and its disks.
If you do not specify the storage policy, the system uses a default storage policy that is associated with the datastore. If your storage requirements for the applications on the virtual machine change, you can modify the storage policy that was originally applied to the virtual machine.