gtps3m0rSystem Performance and Measurement Reference

Details of File Reduction

Random File Access Summary - Total Accesses Per Second

Data write, data read, and program read counts are accumulated each interval, divided by seconds, and added together to equal total accesses per second during a given interval. The total accesses are then accumulated for the mean. At the end of the tape, the accumulation for the mean is divided by the number of intervals.

Random File Access Summary - Device Queues Mean

Device queue counts are sampled every access, accumulated each interval, divided by samples, and accumulated for the mean. At the end of the tape the accumulation for the mean is divided by the number of intervals.

Random File Access Summary - Total System

 Method: 
VFA accesses are not considered to be random file accesses. DASD accesses are considered to be random file accesses.

 Result: 
The total system line excludes VFA accesses and includes DASD accesses.

Sequential File Access Summary - YYY Module

A symbolic tape name of YYY denotes that a specified tape drive was inactive at the start of the collection, and that an unspecified tape was mounted on that tape drive or varied online during the collection.

File Accesses Per Record ID Report

 Method: 
Program access IDs are collected as non-printable EBCDIC codes.

 Result: 
An ID of '--' indicates that a program access ID has been intercepted.