Rebuild can be initiated by an authorized program, by an operator, or by MVS™. For each structure affected by the rebuild request, the system determines whether to start a rebuild or duplexing rebuild and, if started, which method (user-managed or system-managed) to use.

• A user-managed rebuild is initiated if there is at least one active connector to the structure and all active connectors have specified or defaulted to IXLCONN ALLOWREBLD=YES. The specification of IXLCONN ALLOWAUTO is not considered.
• A user-managed duplexing rebuild is initiated if there is at least one active connector and all active connectors have specified IXLCONN ALLOWDUPREBLD=YES.
• A system-managed rebuild will be initiated if a user-managed rebuild is not initiated and the following conditions are met:
  • There is at least one active connector and all connectors have specified IXLCONN ALLOWAUTO=YES.
  • There are no active connectors to the structure. The specification of IXLCONN ALLOWAUTO is not considered.
  • The CFRM couple data set supports SMREBLD.
• A system-managed duplexing rebuild will be initiated if the following conditions are met:
  • There is at least one active or failed-persistent connector and all connectors have specified IXLCONN ALLOWAUTO=YES.
  • There are no active or failed-persistent connectors and the CFRM active policy indicates that the structure had previously been duplexed.
  • All active connectors have connectivity to the simplex instance of the structure.
  • There are no connectors that could not be reconciled into the active policy for the structure.
  • The structure is not marked as failed.
  • The structure is system-managed duplexing-capable (allocated in a coupling facility of CFLEVEL=11 or higher and allocated by a system at OS/390® Release 8 or higher).
  • There is at least one other coupling facility of CFLEVEL=11 or higher in the preference list.
  • The CFRM couple data set supports SMDUPLEX.
  • There are no pending policy changes for the structure.