VSAM optimization

For sequential accesses, Data Optimizer manages index and data buffer values. For random accesses, Data Optimizer dynamically builds and uses LSR buffer pools without changes to the application. For accesses that indicate random and sequential access, Data Optimizer records history to learn how to best optimize future processing by the application. When Data Optimizer has selected LSR processing, if the application proceeds to perform significant sequential accesses, Data Optimizer can perform its own read-ahead processing to continue providing sequential performance benefits. For NSR and LSR optimization, Data Optimizer moves buffers and control blocks above the 16 MB line (when possible) to aid in virtual storage constraint relief.

The following figure shows the VSAM performance component of Data Optimizer.