Fabric administrators create storage reservation policies to allow tenant administrators and business group managers to assign the volumes of a virtual machine to different datastores for the vSphere, KVM (RHEV), and SCVMM platform types.
Assigning the volumes of a virtual machine to different datastores allows tenant administrators and business group managers to control and use storage space more effectively. For example, they might deploy the operating system volume to a slower, less expensive datastore and the database volume to a faster datastore.
Tenant administrators and business group managers can assign a single datastore or a storage reservation policy that represents multiple datastores to a volume. When they assign a single datastore to a volume, vRealize Automation uses that datastore at provisioning time, if possible. When they assign a storage reservation policy to a volume, vRealize Automation uses one of its datastores at provisioning time, if possible.
A storage reservation policy is essentially a tag applied to one or more datastores by a fabric administrator to group datastores that have similar characteristics, such as speed or price. A datastore can be assigned to only one storage reservation policy at a time, but a storage reservation policy can have many different datastores. A fabric administrator creates a storage reservation policy and assigns it to one or more datastores. A tenant administrator or business group manager then assigns the storage reservation policy to a volume in a virtual blueprint. When a user requests a virtual machine that uses the blueprint, vRealize Automation uses the storage reservation policy specified in the blueprint to select a datastore for the machine’s volume.
If you have SDRS enabled on your platform, you can allow SDRS to load balance storage for individual virtual machine disks, or all storage for the virtual machine. If you are working with SDRS datastore clusters, conflicts can occur when you use reservation policies and storage reservation policies. For example, if a standalone datastore or a datastore within an SDRS cluster is selected on one of the reservations in a policy or storage policy, your virtual machine storage might be frozen instead of driven by SDRS.