Before the Duplex Established Phase

If the old structure fails before the Duplex Established phase, MVS™ presents the STRFAIL event for the old structure to all connectors and then stops the duplexing rebuild to fall back to the old structure. Connectors might need to disconnect, or can attempt to rebuild the structure, if possible.
If the new structure fails before the Duplex Established phase, MVS stops the duplexing rebuild to fall back to the old structure and notifies connectors through the STOPDUPLEX reason code that they should attempt to duplex the structure. MVS does not present the STRFAIL event for the failure of the new structure.