When a fabric has multiple Subnet Managers, you must configure some parameters uniquely and some identically.
Subnet Manager Priority – Subnet Managers can have different Priority values. The overall priority is determined from both the switch's GUID and the Priority value. Configure the Subnet Managers with the highest Priority value first, then configure any remaining Subnet Managers.
Subnet Manager Prefix – All Subnet Manager must use the same prefix. Configure the standby Subnet Managers first, then configure the master Subnet Manager.
Subnet Manager Controlled Handover – All Subnet Manager must use the same configuration for controlled handover. Configure the standby Subnet Managers first, then configure the master Subnet Manager.
Subnet Manager Routing Algorithm – All Subnet Manager must use the same routing algorithm. Configure the standby Subnet Managers first, then configure the master Subnet Manager.