A Virtual Volumes (VVol) datastore represents a storage container in vCenter Server and the vSphere Web Client.
After vCenter Server discovers storage containers exported by storage systems, you must mount them as Virtual Volumes datastores. The Virtual Volumes datastores are not formatted in a traditional way like, for example, VMFS datastores. You must still create them because all vSphere functionalities, including FT, HA, DRS, and so on, require the datastore construct to function properly.
You use the datastore creation wizard in the vSphere Web Client to map a storage container to a Virtual Volumes datastore. The Virtual Volumes datastore that you create corresponds directly to the specific storage container. The datastore represents the container in vCenter Server and the vSphere Web Client.
From a vSphere administrator prospective, the Virtual Volumes datastore is similar to any other datastore and is used to hold virtual machines. Like other datastores, the Virtual Volumes datastore can be browsed and lists virtual volumes by virtual machine name. Like traditional datastores, the Virtual Volumes datastore supports unmounting and mounting. However, such operations as upgrade and resize are not applicable to the Virtual Volumes datastore. The Virtual Volumes datastore capacity is configurable by the storage administrator outside of vSphere.
You can use the Virtual Volumes datastores with traditional VMFS and NFS datastores and with vSAN.
The size of a virtual volume must be a multiple of 1 MB, with a minimum size of 1 MB. As a result, all virtual disks that you provision on a Virtual Volumes datastore must be an even multiple of 1 MB. If the virtual disk you migrate to the Virtual Volumes datastore is not an even multiple of 1 MB, extend the disk to the nearest even multiple of 1 MB.