While you can see which disks are included in a disk group, or where a VM is staged from the vSphere Web Client, you can get detailed disk utilization and distribution information from the table rendered by this command.
As we are asking for information about the VSAN cluster, the command will be executed against the cluster level in RVC.
vsan.disks_stats /<vCenter>/<Datacenter>/computers/<Cluster>and strike the Enter key:
Here, we can see information about our disks. We can see what type of disk it is (isSSD), that we have components on all disks (Num Comp), how much of the disk is used (Used), and its state (Status Health).