IBM ServeRAID-4 Ultra160 Series User Reference page 139

v Set the logical drives to non-shared by changing the merge group IDs. Use the
offline version of the ServeRAID Manager program to make this change.
Note: If you use the online version of the ServeRAID Manager program to delete
and recreate the logical drives that have the same merge group ID, you
will not be able to access the logical drives. You must delete the logical
drives, restart the server, and recreate the logical drives.
Chapter 14. Installing the Microsoft Cluster Service software
121