Message recovery

IMS assures that messages are not lost or duplicated across a Multiple Systems Coupling (MSC) link by logging information about a message in both the sending and receiving systems.

IMS restores this information during restart and exchanges it between the systems after the link is established. The sending system can then dequeue a message that was received by the receiving system but for which the acknowledgment was lost due to a link or system failure. The sending system can also re-send a message that was sent but not enqueued by the receiving system. If an IMS subsystem fails to recover, the messages for which it has recovery responsibility are lost.

Because IMS provides commands to dynamically change link assignments, you can set up an alternate processor for an inoperable one. The IMS system that resides in the inoperable processor can run in the alternate processor after all involved links are properly reassigned by the master terminal operators (MTOs).