Is it dependant upon how many disk groups there are? All I've been able to see from the various videos and other materials is that once the vsan cluster is created and disks are added - a single data store is created on all of the space.
But - if there are alot of disks across all the hosts in the cluster, do we really want to create a gigantic data store?
Yes - only one VSAN Datastore is created per VSAN cluster. Don´t mix it with block based thoughts - think of it more than an object centric model. Thus, it makes sense to only have one VSAN datastore per cluster.
It is worth to go through this thread as well :