During IPL the system needs to dynamically determine for PPRC pairs with the same device number whether the subchannel in the primary subchannel set should be connected to the UCB or the subchannel in an alternate subchannel set should be connected. The actions performed by IOS for a PPRC pair with the same device number depend on the state of the device with respect to the copy services relationships and the SCHSET parameter specified in LOADxx. If the parameter was not specified in LOADxx or is not valid, and at least one PPRC pair exists with the same device number, the operator is required to make a choice.