When you use Virtual SAN, you can define virtual machine storage requirements, such as performance and availability, in a policy. Virtual SAN ensures that each virtual machine deployed to Virtual SAN datastores is assigned at least one storage policy.
After they are assigned, the storage policy requirements are pushed to the Virtual SAN layer when a virtual machine is created. The virtual device is distributed across the Virtual SAN datastore to meet the performance and availability requirements.
Virtual SAN uses storage providers to supply information about underlying storage to the vCenter Server. This information helps you to make appropriate decisions about virtual machine placement, and to monitor your storage environment.