New Connections

Rebuild
The system will fail an IXLCONN invocation for a new connection during system-managed rebuild with return code (X'0C'), reason code IXLRSNCODECONNPREVENTED (X'xxxx0C09').
Duplexing Rebuild
New connections (or reconnections) to a duplexed structure during the Duplex Established phase are permitted assuming the connector allows system-managed processes by specifying ALLOWAUTO=YES on IXLCONN. When this criterion is not met, the connect request while the structure is Duplex Established is rejected with reason code IXLRSNCODECONNPREVENTED (X'0C09').

When the connect is permitted, connect processing will transparently attach the connector to both structure instances of the duplex pair, and initialize the connection so that all coupling facility operations that are subsequently performed by the new connector are duplexed appropriately.
The connect request, when successful, will complete either with return code 0 when none of the “special conditions” for connect processing apply, or with reason code X'0407' (IXLRSNCODESPECIALCONN) when one or more of the defined “special conditions” do apply at connect time. These “special conditions” include:
- Reconnected
- User sync point in progress
- Alter in progress
Note that the “rebuild in progress” condition is used to inform the connection that it needs to participate in the process and since system-managed processing does not require connection participation, the condition does not apply.

If at the time of the connect request, the duplexed structure has no active connectors, and the primary and secondary structures are both inaccessible from all systems in the sysplex, the system will force the deallocation of both of the duplexed structure instances. The system will then retry the connect request to cause a new structure instance to be allocated in some accessible coupling facility. Once a new instance of the structure is allocated, it may become duplexed.
If the new connector does not have connectivity to both instances of the duplexed structure, the connect request will be processed as follows:
- The system will automatically initiate duplexing rebuild stop processing to revert to simplex mode, keeping either the primary structure instance or the secondary structure instance, whichever the connector has connectivity to. The duplexing stop processing will proceed asynchronously with respect to the additional connect request retry processing described below, and it will internally suppress any attempt to automatically reduplex the structure at the time that the duplexing rebuild stop/switch processing completes.
- The unsuccessful connect request will be internally deferred and retried for a period of time, trying to catch the structure after it has reverted to simplex mode.
- When the duplexing rebuild stop/switch processing completes, duplexing will not be automatically re-initiated at that time. This allows the structure to remain in simplex mode to accomodate the retried connect request.
- If the retried connect request to the structure in simplex mode is successful, and the connector still has connectivity to the surviving simplex structure at that time, the connect request succeeds. An attempt to reduplex the structure will be triggered by the successful connect request to try to reestablish duplexing in some other coupling facility to which all of the current connectors have connectivity.
- While stop/switch processing is in progress for the structure, if none of the retried connect requests is successful connecting to the structure in simplex mode, then the connect request will fail with an indicative return and reason code indicating that the connector cannot connect to the structure.
  However, subsequently when the structure eventually completes its stop or switch processing, an ENF 35 for structure availability will be issued. If the connector listens for ENF 35 signals, the connect request can be retried in response to that signal, and the connector can connect to the structure in simplex mode (and again, this successful connect will serve as a trigger to reduplex the structure). If the connector does not reattempt the connect in response to the ENF 35 signal, then the structure may remain unduplexed until such time as duplex enabled monitoring attempts to reestablish duplexing for the structure.