it's in the bin file that resides on the service processor. When you create/delete/modify devices with SMC/ECC/symcli ..bin file reflects those changes.
In compare to HDS how the device mapping database kept in EMC DMX ?? I know in HDS its get stored it Sequel Database format . I belive in EMC its get storage in flat file format. is this true ?? Is the format got changed in new V-Max  That is why when we compare HDS USP with EMC DMX/VMAX they do put forward this point , so because of Sequel DB for they are more faster.  Device mapping db is mapping Meta to hypers and hypers to slice of disk.  
Device mapping database