Device numbers

When multiple systems are migrated to a z17, the combination of systems could include different devices or shared devices with identical device numbers. Each system can operate in an LP without changing the device numbers as long as identical device numbers do not occur in the same LP. However, duplicate device numbers can exist in the same LP if these device numbers are in different subchannel sets.

Duplicate device number conflicts can occur when the I/O configuration is reconfigured. For example, if a reconfigurable channel path is reassigned to another LP and devices attached to the channel path have device numbers that are already assigned in the receiving LP to other online channel paths, a conflict results. When IOCP generates an LPAR IOCDS, the initial configuration contains no duplicate device number conflicts in an LP.

Device number conflicts are also detected when operator tasks change the I/O configuration (channel path tasks from the Hardware Management Console or Support Element console; or control program configuration command) or during LP activation.

Duplicate device number conflicts are also detected when a dynamic I/O configuration change is made.