For an XMP processor, you can define a channel path that is not physically installed on the machine. This may be useful if you want to migrate from a machine with more channels defined than the target XMP processor has currently installed, or if you want to prepare a configuration for future upgrades of the channel cards.
You can also over-define CIB channel paths for your OS partition. This avoids an outage for the definition of new CIB connections between an OS partition and a stand-alone coupling facility CPC.
To distinguish an over-defined CHPID from a physically installed CHPID, use character * for the PCHID value or the HCA ID for CIB channels, when over-defining the CHPID. An over-defined CHPID must adhere to all validation rules.
When installing the channel path later, you must edit the CHPID and replace the * by its valid PCHID or HCA ID.
Over-defined channel paths are not taken into account by an IOCDS download, by an IOCP build and by a dynamic activation of an I/O configuration. If a control unit contains only CHPIDs with a PCHID value or HCA ID *, the whole control unit (including any attached devices) is omitted from the configuration.
If a CHPID changes its PCHID or HCA ID from * to a valid value during a dynamic activation, an Add CHPID request is generated. Correspondingly, if the PCHID or HCA ID is changed from a valid value to an *, a Delete CHPID request is generated.
When building a CONFIGxx member, CHPIDs with a PCHID/HCA ID * are skipped. Attached control units including attached devices are also omitted.
When copying a configuration or generating I/O configuration statements, channel path definitions with PCHID=* and AID=* are included.
When building a production IODF, HCD requires that the CIB channels are connected, even if they are over-defined. If the connection is within the same processor, a mix of over-defined and fully-defined HCA IDs is not accepted. In this case, error message CBDG541I is issued and the production IODF is not built.