Please share some EMC.Com (Tech Tips) regards to difference in NAS for Integrated and Gateway Model?

Celerra - NAS Storage Platform from EMC features are really impressive depending on the model customer purchase. EMC Celerra's main hardware components are Control Station, Data Mover and Backend Storage (which could be CLARiiON or DMX). In integrated models all storage volume allocation configuration for NAS are done through control station without loging to Backend Storage (done through inbuilt batch script); whereas in gateway model BAckend Storage is a different component and Celerra Gateway model is a different component; hence in gateway we need to zone celerra to backend CX or DMX; then for allocating volumes to Celerra we need to login to backend storage like DMX or CX.

In short
Gateway - Doesn't have integrated CX or DMX (Fabric switch or direct connect. If switch involved then need to zone with data mover and CX or DMX)
Integrated - The CX or DMX is included in NAS (no need to zone or switch not involved)

How to move CIFS from PDM to VDM?

There is a process within EMC to move the PDM to VDM for CIFS environment. Moving PDM to VDM requires EMC approval and EMC approved documents and would need to engage a real Celerra expert. This is typically done by cifs_move command. EMC recommends CIFS environment to be on VDM. Downtime required to move from PDM to VDM on production environment; it could be 2 to 3 hours for moving and validation.