A structure in the Duplex Established phase of a user-managed duplexing rebuild or system-managed duplexing rebuild can be altered.

If a structure is in user-managed duplexing rebuild processing when the IXLALTER request is received, the alter is applied to both instances serially. The primary (old) structure is altered first. When the alter for the old structure instance is complete, the secondary (new) structure is altered. The connectors are notified that the alter has started and completed for each structure instance individually through their event exits.

If a structure is in system-managed duplexing rebuild processing when the IXLALTER request is received, the alter is applied to both instances serially with the primary (old) structure being altered first followed by the alter of the secondary (new) structure. However, the connectors are notified that the alter has started and completed only once, treating the alter operation as if it were performed against one virtual structure.