This KB explains how to map data store display names to the internally used data store MOIDs.
VMware vCenter Server
The mapping between the datastore ID (Storage Id) and the datastore name viewable in the UI within the vSphere environment can be confirmed using the Managed Object Browser (MOB) or PowerCLI.
Select the link in the VALUE column associated with NAME:rootFolder (expected to be group-## (Datacenters)).
Select the link in the VALUE column associated with NAME:childEntity (expected to be datacenter-## (<DatacenterName>)).
Confirm the datastore MOID and the display name from the VALUE column associated with NAME:datastore.
Connect to the vCenter Server using the Connect-ViServer cmdlet.
Run the command Get-Datastore | Select-Object Id,Name to confirm the datastore ID and the display name.
For more information about the Get-Datastore cmdlet, refer to Get-Datastore.