User-managed duplexing rebuild is available only for cache structures. User-Managed Duplexing Rebuild Timeline summarizes the phases associated with the user-managed duplexing rebuild process.

The following list summarizes that process:

1. Duplexing rebuild for a structure is initiated through SETXCF START,REBUILD,DUPLEX or IXLREBLD REQUEST=STARTDUPLEX. or internally by MVS™.
2. The system reports the Rebuild Quiesce event to connector's event exit.
3. Connector stops activity to the original structure and issues IXLEERSP EVENT=REBLDQUIESCE to respond to the event.
4. When all IXLEERSP responses are received, the system reports the Rebuild Connect event to the connector's event exit.
5. Connector issues IXLCONN REBUILD for the structure. If the first to issue IXLCONN, the connector allocates the new structure; otherwise, the connector connects to the new structure. The system revalidates the token to access the old structure and provides a new token to access the new structure.
6. Connectors propagate data to the new structure to synchronize both structures and issue IXLREBLD REQUEST=COMPLETE when finished.
7. When all IXLREBLD REQUEST=COMPLETE requests are received, the system reports the Duplex Established event to each connector's event exit.
8. Connectors continue in duplexed mode until a request is received to stop the duplexing and either fall back to the old structure or forward complete (switch) to the new structure.
9. If a fall back to the old structure is requested, the system reports the Rebuild Stop event to connector's event exit. See Summary of Rebuild and Duplexing Rebuild Stop Processing.
   • Connector quiesces use of both structures, completes any necessary processing for the new structure, and issues IXLREBLD REQUEST=DUPLEXCOMPLETE.
   • When all connectors have issued IXLREBLD REQUEST=DUPLEXCOMPLETE, the system reports a Rebuild Cleanup event to each connector's event exit. Connector must issue IXLEERSP to respond to the event.
10. If a switch to the new structure is requested, the system reports a Rebuild Switch event to connector's event exit.
    • Connector cleans up references to the old structure. The original token is used to access the new structure.
    • When all IXLEERSP responses are received, the system reports a Rebuild Process Complete event to each connector's event exit.
11. Connector resumes processing with the remaining structure.