Part V: Batch Architecture at Scale

"Online gets the glory. Batch does the work. Every night, while the world sleeps, batch jobs process the transactions, calculate the interest, generate the statements, update the balances, and reconcile the books. When batch fails, the bank doesn't open in the morning."

What This Part Covers

Part V is the art of processing a billion records overnight. Five chapters cover batch window engineering, checkpoint/restart design, parallel processing, performance optimization, and the monitoring and incident response procedures that keep batch running — or get it running again when it fails.

Batch processing is the backbone of enterprise computing, and it's the area where COBOL's strengths shine brightest. But designing batch systems that process hundreds of millions of records within a fixed window, survive any failure without data loss, and scale with growing volumes requires architectural thinking that goes far beyond writing a READ-PROCESS-WRITE loop.

Continental National Bank's end-of-day batch window processes every transaction from the day, calculates positions, generates regulatory reports, and must complete before online comes up at 6am. Pinnacle Health Insurance's monthly claims adjudication run processes 50 million claims through a multi-step pipeline. Both push the limits of what batch can do.

Chapters in This Part

Chapter Title Key Question
23 Batch Window Engineering How do you fit everything into the window?
24 Checkpoint/Restart Design How do you survive any failure without reprocessing?
25 Parallel Batch Processing How do you process partitioned data across multiple tasks?
26 Batch Performance at Scale How do you optimize I/O, buffers, and SORT at scale?
27 Batch Monitoring and Incident Response How do you know when something is wrong — and fix it fast?

Progressive Project

You'll design the complete batch architecture for your HA banking system: the job stream for end-of-day processing, checkpoint/restart logic, parallel processing for the transaction posting pipeline, performance-tuned SORT and I/O operations, and the monitoring and alerting framework that pages the on-call team when the batch window is in danger.

Prerequisites

Part I (Chapters 1, 4, 5). JCL fundamentals from Books 1 and 2.

Chapters in This Part