Capacity Planning for PeopleSoft

PeopleSoft is a complex multi-functional, multi-tier application. Important questions about its configuration, load balancing and capacity planning need to be answered during its deployment and production use. This paper describes an approach to answering such questions for the most commercially important configurations of PeopleSoft (3-tier, 2-tier and mixed). It covers architectural features and available measurements relevant to performance analysis and capacity planning. Comprehensive treatment of all the information sources is necessary for the solution. 1. Performance analysis of an application Before dealing with PeopleSoft let us consider what it means to analyze performance and do capacity planning for an application. These activities can be subdivided into several related but distinct areas. 1.1 Workload characterization This activity provides information for day-today performance management and monitoring, as well as the foundation for modeling what-if performance questions. It can also be used to derive data for sizing, as described in the next section. To characterize workloads (and in real production environments there are usually multiple workloads to be distinguished) the following needs to be done: • Resource consumption for different types of work, e.g., business functions, should be determined • Relationships among different steps of transaction execution, i.e., different layers and servers should be established • Counts of business units of work need to be obtained, or at least ratios of those counts in different situations Under distributed systems, e.g., UNIX or NT, the user visible representation of application work is a collection of system processes. Therefore, the first approach to the above tasks lies through identification of the role of relevant application processes and their relationships. As the first cut of workload characterization an analyst should do the following: • Identify the list of processes doing the work of the application under study • Identify client-server relationships, if any, among the processes • Determine if the user-relevant breakdown of work by business function could be specified at the process level Additional measurements describing the workload composition may be provided by the database, if used, or by the instrumentation of the application itself. Most major databases provide some relevant information, whereas the level of applications instrumentation varies widely from case to case. 1.2 Sizing using resource utilization profiles This analysis requires resource utilization breakdown by specific types of business functions (a.k.a., units of work or transactions). Benchmarking is usually needed to obtain resource profiles for the appropriate types of work. The profiles include resource consumption at different servers, hardware and software, and are suitable inputs for analytic modeling. They allow the user to do sizing in the absence of a running system or to test-drive the effect of adding new loads to the loads already present. 1.3 Application architecture-specific modeling Several areas of architecture can be listed: • memory (buffers) use and the resulting saturation behavior • internal application scheduling and prioritization • number and type of configured service components These architectural features usually require targeted benchmarking and additional algorithms to represent them. Little has been published about capacity planning for PeopleSoft and especially about the most common configurations moving into the corporate IS. One recent paper, [CHU98], addresses derivation and modeling of service demand for low-level requests resulting from application activities such as update, insert, etc. However the problem of characterizing workload on a working system, as described in Workload Characterization above, was not covered in that paper, and indeed anywhere to date, to the authors’ knowledge. This problem is the main topic of the present paper. 2. PeopleSoft architecture In order to approach workload characterization, relevant architectural attributes of PeopleSoft need to be presented. Until version 7, PeopleSoft was typically used as a 2-tier system where clients would be connected directly to the database server. Occasionally, ad hoc middleware would be introduced between clients and the database as an application server. Starting with Version 7 (current PeopleSoft version) in addition to 2-tier client/server architecture PeopleSoft provided a 3-tier model with a PC client and a TUXEDO application server. This introduced a level of standardization into the 3-tier configuration and made its capacity planning important for an increasing number of users. The major advantages of the 3-tier configuration are significant performance gains (especially with PeopleSoft 7.5) and a reduction in the network traffic. At the same time 2-tier and 3-tier versions can and do coexist in the same implementation at most sites. Hence one needs to consider both versions and design an approach valid in a mixed environment (see Fig.1). Application Server A TUXEDO Domain X Payroll PC Client PC Client PC Client Application Server B TUXEDO Domain Y Manufact. PC Client Web Server Web Client 3-tier PC clients RDBMS Instance DB Server