Loss of connectivity to the coupling facility structure

If a structure was in duplex-mode and a loss of connectivity occurs to only one instance of the structure (due to a hardware link failure), then XES will automatically switch from duplex-mode to simplex-mode. Logger will only be notified of the mode switch change and will not be aware of any loss of connectivity to the structure. See When the coupling facility structure duplex/simplex mode changes for how Logger handles mode switches for the structure.

For a simplex-mode structure, Logger detects the loss of connectivity to the single instance of the structure. Then, based on the rebuild threshold specified, if any, in the structure definition in the CFRM policy, the system that lost connectivity may initiate a rebuild for the structure.

If a rebuild is initiated, the event 48 parameter list mapped by macro IXGENF has bits IXGENFLogStreamsNotAvailable, and IXGENFStrRebuildStart, on, and field IXGENFStrName contains the name of the coupling facility structure affected. System logger rejects logger service requests issued during the rebuild process.

If XES cannot allocate a new structure instance in a coupling facility that can be connected to all the affected systems, system logger does one of the following, depending on whether the system or systems that cannot connect to the new coupling facility structure were using staging data sets:

If the system was using staging data sets, the rebuild process continues and the coupling facility log data for the system is recovered from the staging data sets.
If the system was not using staging data sets, the rebuild process is stopped. The systems go back to using the source structure.
The systems that do not have connectivity to the old coupling facility structure issue an ENF 48 event indicating that they do not have connectivity to the log stream.

The systems that can connect to the source structure issue an ENF 48 event indicating that the log stream is available to that system and can resume use of the log stream.

The installation should either update the CFRM active policy to make the new coupling facility structure available to all the systems or else fix the hardware link problem and then have the operator initiate a rebuild for the structure so that all the original systems will have connectivity.