GT.M does not make any decisions regarding primary or secondary operation of an instance. A mechanism external to GT.M is needed to identify system status and to determine the primary and secondary systems. Use this mechanism during application startup.

To implement a robust, continuously available application, it is important that each application instance comes up in the correct state. In particular, there must be exactly one primary and either no secondary system or one secondary system. All database update operations on replicated databases must take place only on the primary, and there must be no logical database updates on the secondary.

	Note
	/mupip backup /online and mupip reorg /online update control information in the file header, not the database contents, and can operate freely on the secondary.