Which type of storage entity is used as the backing disks for persistent volumes in...

https://docs.vmware.com/en/VMware-vSphere/7.0/vmware-vsphere-with-tanzu/GUID-1B136277-E46C-41FC-9C8C-3E78E9B97F5C.html

vSphere with Tanzu uses the First Class Disk (FCD) type of virtual disks to back persistent volumes. FCD, also known as Improved Virtual Disk, is a named virtual disk not associated with a VM. FCDs are identified by UUID and can be managed independently of VMs.

Thick provisioned VMDK, Raw Device Mapping (RDM), and Virtual Volumes (vVOLs) are not used as the backing disks for persistent volumes in vSphere with Tanzu.

The references are:

Using Persistent Storage in vSphere with Tanzu, section “Persistent Volume”

vSphere with Tanzu Storage, section “First Class Disk”