You cannot specify which SPM will serve as the DCU SPM or PDomain SPM, but you can specify that Oracle ILOM should assign a new SPM in the pair to serve these roles. You might do this when, for example, you are replacing an SPP.
Complete this task to change the current roles of the SPMs. For example, you would need to change the SPM in the pair that is currently identified as the DCU SPM to be the Standby SPM if you are replacing it.
-> set /System/DCUs/DCU_x initiate_sp_failover=true