Database Reference
In-Depth Information
CHAPTER 24
SAP System Sizing Overview
In this chapter we will study the significance of SAP sizing and explore an overview of the
entire SAP sizing process. We will also study SAP sizing theoretical concepts; tools provided
by SAP to aid the customer in the sizing process, such as Quick Sizer; different kinds of siz-
ing approaches; and some specific examples of sizing SAP solutions, such as ERP, BW, and
network sizing. SAP sizing projects are started in a new SAP implementation and are updated
throughout the lifecycle of the SAP projects from the blueprint design stage to the post-go
live and upgrade stages of the projects. SAP recommends using different sizing approaches
depending upon the stage of the project. When a new SAP project is in the design stages the
infrastructure team is charged with performing an initial budget sizing to get an understand-
ing of the costs of the servers and related technology that would be required for the project.
This is followed up with iterations of sizing by closely working with the business teams until
realistic user and expected volume information is provided to the sizing tool to calculate the
needed hardware for the project.
Significance of SAP Sizing
Performing a SAP sizing at the beginning of the project is very important for several reasons.
Foremost is to make sure that the performance and response time expectations of the business
users are met by planning and providing adequate system resources before the projects goes
live. Since ERP projects are major changes in an organization, it is very important to provide
the data availability to the end users for a system that is being implemented as a system of re-
cord. This will make the end users embrace the system and champion it to the remaining
business users inside the organization. Other reasons for performing a sizing project and to
keep it updated are to not overspend on infrastructure that would not be utilized and would sit
idle. A good sizing effort will help the infrastructure team to plan and procure the appropriate
amount of system resources (CPU, memory, and disk) on time, considering that the lead
times for the procurement process and vendor delivery could be considerable.
Sizing Theory and Practice
SAP sizing is based on a theoretical concept called the queuing model (or queuing theory). In
this kind of modeling the queuing systems are studied mathematically to estimate the per-
formance criteria such as response times. A SAP three-tiered software architecture is studied
as a queuing model with one service center (CPU). In this three-tiered SAP architecture, all
the major system resources, such as memory, disk, and network load, can be spread out in
such a way that any queuing can be significantly reduced. However, the CPU of the database
server is the single most-limiting factor in a three-tiered SAP software architecture and is,
