Understanding the Performance Implications of Buffer-to-Buffer Credit Starvation In a FICON Environment: Frame Pacing Delay

摘要

This paper will give a brief review on buffer-to-buffer credits (BB_credits) including current schema for allocating/assigning them. It will then discuss the one method currently available to detect BB_credit starvation on FICON directors, including a discussion on the concept of frame pacing delay. Finally, the author will outline a concept for a mechanism to count BB_credit usage. The paper will conclude with a discussion of another theoretical "drawing board" concept: dynamic allocation of BB_credits on an individual I/O basis similar to the new HyperPAVs concept for DASD.