Disk

1. One of datastore_id or datastore_cluster_id must be specified.
2. Use of datastore_cluster_id requires vSphere Storage DRS to be enabled on the specified datastore cluster.
3. The datastore_cluster_id setting applies to the entire virtual machine resource. You cannot assign individual individual disks to datastore clusters. In addition, you cannot use the attach setting to attach external disks on virtual machines that are assigned to datastore clusters.

references:

1. vsphere_virtual_machine | Resources | hashicorp/vsphere | Terraform Registry