Loss of connectivity to the coupling facility structure

If a system loses connectivity to the coupling facility structure due to a hardware link failure, all the systems connected to the log streams associated with the coupling facility detect the failure.

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 coupling facility that all the systems affected can connect to, 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 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.

Applications must listen for another ENF event 48 to learn the status of the log stream after rebuild processing is complete. The status will be one of the following:

The structure rebuild has completed successfully, the coupling facility structure and associated log streams are available, and system logger requests will be accepted. Bits IXGENFLogStreamsAvailable and IXGENFStrRebuildComplete are on in the event 48 parameter list mapped by macro IXGENF.
The structure rebuild was unsuccessful. Connections to the structure are not available because the system receiving the ENF event code has lost connectivity to the structure.
All system logger service requests against the log streams will be rejected. Bits IXGENFLogStreamsNotAvailable, IXGENFStrRebuildFailed, and IXGENFRebuildFailLossConn are on in the event 48 parameter list mapped by macro IXGENF.