please, take a look at "Configuring NDMP Backups on EMC Celerra" on Powerlink.
Back up a VDM file system with NDMP
This procedure explains only the NDMP-specific guidelines for Virtual Data Mover (VDM).
Configuring Virtual Data Movers for Celerra
provides more information on VDM.
A VDM enables you to administratively separate CIFS servers and their associated resources, like file systems, into virtual containers. These virtual containers allow administrative separation between groups of CIFS servers, enable replication of CIFS environments, and allow the movement of CIFS servers from Data Mover to Data Mover. In a CIFS environment, when you use NDMP to back up a VDM configured file system, you must specify the full mount path of the file system.