After you enable Virtual SAN on a cluster, a single Virtual SAN datastore is created. It appears as another type of datastore on the list of datastores in addition to VMFS and NFS.

A Virtual SAN datastore uses multiple storage components, or disk groups, distributed across the ESXi hosts in the cluster.

A single Virtual SAN datastore provides different Quality of Service (QoS) levels for each virtual machine or each virtual disk.

In the vCenter Server, storage characteristics of the Virtual SAN datastore appear as a set of capabilities. You can reference these capabilities when creating a storage policy for virtual machines. When you later deploy virtual machines, Virtual SAN uses this policy to place virtual machines in the optimal manner based on the virtual machine requirements.

See About Virtual Machine Storage Policies.