1)   Device GroupsA device group (DG) is a user-defined group comprised of devices that belong to asingle Symmetrix array and a single RDF (RA) group. A control operation can beperformed on the group as a whole, or on the individual device pairs that comprise it.By default, a device cannot belong to more than one device group and all of the STDdevices in a group must reside on the same Symmetrix array. However, if theSymmetrix options file parameter SYMAPI_ALLOW_DEV_IN_MULT_GRPS isenabled, a device can be added to multiple groups. You can use device groups toidentify and work with a subset of available Symmetrix devices; obtain configuration,status, and performance statistics on a collection of related devices; or issue controloperations that apply to all devices in the specified device group.  2) you can run "symdg show
Hi  1. What is the use of device group in symmetrix. 2. What all the specfic commands we can use to get detail about list of device groups configured in symmaetrix 
Device Group in Symmetrix