Required permission to query orphaned VMDK files

Hi,

What is the specific required permission to query vSphere for orphaned vmdk files? Right now my account has a ReadOnly role in vCenter and when I run a PS script to find orphaned VMDks, I'm getting an error complaining about the permission.

I know it's included in the Administrator role in vCenter, but I was wondering if that specific permission can be added to a custom role, without having to be given Administrator role?

This is for an auditing project, so the VM admins gave us the absolute minimum permission/role.

Envrionment: ESXi 5.0/vCenter 5.0

If I need to post this in a more relevant community please let me know.

Thanks in advance,

Alex