database server is used both for regular OLTP activity as well as for reporting . there are nightly jobs that are moving the data from the OLTP sets of tables to a data mart created inside the same database for reporting purposes. there is not a high load and the present design does not give performance issues.
data is split on 4 filegrups
1.OLTP data
2.OLTP index
3.data mart data
4.data mart index
Since the storage is on the SAN and traffic going through same pipeline is any advantage to separate the OLTP data and reporting data on separate drives (LUNS cut from the SAN drives) and create 4 drives corresponding to the 4 filegrups above. or it does not really matter for performance if consolidate both the OLTP data and reporting data on one LUN and OLTP indexes and reporting indexes on another (this way creating 2 drives one drive for filegroup 1 and 3 and one drive for 2 and 4)