Perhaps the most important component of a PAI/O Driver for z/OS enterprise user license is the subsystem performance profiles. These licensed documents are provided to our licensed enterprise users to assist them in understanding and acquiring new storage subsystems. These licensed documents are not provided to the vendors as part of their site licenses, and are not written to provide any vendor an independent endorsement of some product.
PAI/O Driver for z/OS subsystem profiles are based on a standard set of engineering tests which are employed by Performance Associates to evaluate each new or updated storage subsystem. The content of these profiles should not be confused with similar sounding product offerings that are based on expert analysis of vendor brochures, anecdotal observations, or vendor supplied data. Rather, PAI/O Driver for z/OS subsystem profiles are based on hard experimental data that is independently collected by Performance Associates employees using the industry standard PAI/O Driver for z/OS tool set which is respected by both users and vendors.
Each subsystem profile is comprised of four major sections. They are:
Architectural Overview
Experimental Results
Observations, Comments, and Hypotheses
Acquisition Strategies
Subsystem profiles range from forty to seventy pages in length depending on the complexity of the subsystem and the number of configurations evaluated.
Architectural Overview
The architectural overview provides a tutorial on the hardware and firmware architecture employed by the system. Key topics include logical and physical structure, fault tolerance, RAID schemas supported, and the logical and physical connectivity provided by the storage subsystem.
Experimental Results
The experimental results section provides the meat of the profile. This section details the configurations that were evaluated as well as the results of Performance Associates’ standard series of tests. These tests evaluate uniform, skewed, online update, record level, front end, and sequential I/O arrival patterns. The results of the standard engineering tests are presented in access density as well as I/O rate formats so that vendor product offerings of difference capacities can be compared by the user.
Observations, Comments, and Hypotheses
The observations, comments, and hypotheses section provides a comprehensive analysis of the results presented in the experimental results section. Observations include topics such as ongoing tuning requirements, aggregate data transfer rate, channel data rate, and an analysis of the storage subsystems scalability. The comments are expressed in a tabular format that highlights the experimental results presented in the profile. The final topic in this section is Performance Associates’ hypotheses about the subsystem. While these hypotheses represent our expert opinions about the subsystem, we are careful to annotate them as our opinions rather than as facts for which we have hard experimental data to support.
Acquisition Strategies
The final section is acquisition strategies. In this section Performance Associates suggests specific terms that should be included in the acquisition contract to protect the user against any deficiencies identified in the subsystem profile.
Summary
To summarize, the subsystem profiles are intended to provide Performance Associates’ licensed enterprise users with independent assessments of vendor storage subsystem offerings. While the standard engineering tests on which the profiles are based do not exactly represent any specific user workload, they do provide the foundation to the PAI/O Driver for z/OS storage subsystem acquisition process. The PAI/O Driver for z/OS profiling and testing software builds on this foundation of knowledge to allow a user to specifically state their requirements to the vendors, and to verify that a vendor product offering has met these requirements in the acquisition process!
