Because the TMC contains the information about the current status of all volumes assigned to CA 1 control, and can significantly affect real-time tape processing, reliable backup and restore capabilities are essential. The batch utility TMSCOPY performs both functions.
The Audit data set is critical to this process. The Audit should reside on a different DASD volume than the TMC (preferably on a different bank/channel). Any real-time, batch, or online update to a TMC record causes an image record to be placed in the Audit data set, with a special code and the date/time stamp of the update.
TMSCOPY backs up the TMC image to two tape volumes (one for vault storage). All Audit records written since the prior TMSCOPY execution are also backed up to tape, and Audit pointers are reset to indicate this action.
The Audit backup data is useful for day-to-day TMC activity reporting, and, in certain instances, can be used in special TMC restore processing.
If a RESTORE is necessary, the latest TMC backup tape is used to recreate the TMC. Then the Audit records written since that backup was taken are automatically applied to the TMC. The resulting TMC is restored to its status at the point of failure.
CA 1 maintains the information as to which Audit records should be applied, how far back to go, when the latest backup was taken and which tape is the latest backup. If another number is presented during restore processing, appropriate warning messages are issued to the console.
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