Availability and Recovery

When activating CTMPLEX, the product uses the Coupling Facility services for communication between the Control‑M's GSM and LSMs, assuring high speed and reliable information transfer between the GSM and all LSMs. The information exchange between Control‑M components can also be stored and maintained by the Coupling Facility itself for recoverability if Coupling Facility malfunction occurs.

Using the Coupling facility services, the Control‑M's GSM automatically detects all LSM or communication failures, assuring that all work associated with the problematic LSM are distributed among other available LSMs until the failure has been corrected. In case of a Control-M's GSM malfunction, the LSM with the highest PRIORITY value replaces the GSM instantaneously to assure an uninterrupted production operation in the Sysplex. When the original GSM restarts, it takes over the GSM function again, since it has the highest PRIORITY value, while the current GSM resumes its LSM role.

If PRIORITY values are changed during the execution of the monitors, the NEWPLEX modify command must be issued to ensure all monitors are working with the same CTMPLEX configuration, and to force the highest priority monitor to become the GSM. Stopping and starting monitors without the NEWPLEX command, may result in a situation where the monitor that is best suited to function as the GSM does not have the highest priority and therefore will only function as an LSM.

CTMPLEX's flexible design and effective operation allows the product to handle the entire Sysplex Batch workload 24x7, without requiring shutdown time for product maintenance. Information is not lost even if one of the Control‑M monitors or LPARS in the Sysplex is not available. The remaining Control‑M monitors automatically updates themselves with any changes that occurred while a Control‑M monitor is unavailable.

In the case of a failure of the Control‑M's GSM, none of the LSMs should be stopped. Just cancel the GSM. This will cause one of the LSMs to switch to GSM, which preserves the CF structure and the data (jobs updates) saved in the CF, and allows the new GSM to read data from the CF structure and perform the required AJF updates.