RDM is recommended as best practice to leverage NetApp SnapManager / SnapDrive features for windows OS earlier than Win2012. VMDK format is supported in win2012 by the latest NetApp SnapManager/SnapDrive.
Can anyone send me some support material or URL related RDM in NetApp environment? e.g. Supported format of the previous and latest SnapManager, New change for Win2012, etc.