cpuhawg
Active User
Joined: 14 Jun 2006
Posts: 331
Location: Jacksonville, FL
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Checkpoints allow an analyst to resubmit a job with a RESTART parameter instructing a program to pick up at a specific point in the program. Checkpoint restarting will NOT work unless the program is written to take checkpoints.
A COBOL programmer can write his program to take checkpoints at specific intervals (say every 10,000 records processed). If you had a million input records, each time the program has processed 10,000 records the program writes a checkpoint with some key field (like policy number) to the output checkpoint dataset. If the job abends (due to a tape drive error or mainframe loss of power), the analyst doesn't have to start the job from the top. He can view the checkpoint dataset, determine the point at which to restart the job, and code his RESTART parameter to begin at that point. The program spins down positioning all the input and output files at the checkpoint and then resumes processing (as well as checkpointing). |
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