Sizing

Background

The process of sizing in SAP implementation involves identifying the hardware requirements, such as CPU power, physical memory, disk space, network bandwidth, and I/O capacity. This iterative process is crucial in translating business requirements into hardware requirements and is typically conducted during the early stages of a project. Its purpose is to ensure that the hardware infrastructure can support the expected workload and performance requirements of the systems and the business processes running on top.

What is SAP Sizing?

SAP sizing involves the collection of business metrics such as users, business transaction document volume, and line items which equates to SAPS (SAP Application Performance Standard) which is a hardware-independent measurement unit representing a throughput processing requirement.

Sizing also needs to take into account whether it's a new implementation, upgrade, or migration as obviously an upgrade or migration may have better numbers from an existing production environment (e.g. SAP EarlyWatch report, or some monitoring report).

Sizing Models

To facilitate sizing, three distinct and separate sizing models have been recognized by SAP.

1. User-based Sizing

User-based sizing involves taking into account the level of activity of users within the system to determine the appropriate size requirements. The accuracy of this estimation model can be limited since it does not provide a detailed understanding of the exact workload generated by these users within the system.

2. Throughput-based Sizing

Using actual or expected throughput as a basis, throughput-based sizing provides a more comprehensive approach. However, there is still a need to validate assumptions regarding business terms such as the number of line items produced annually against individual installation.

This sizing model, together with User-based Sizing, has been integrated into the Quick Sizer tool.

What is SAP Quick Sizer?

SAP Quick Sizer is a questionnaire-based tool that does a pretty good job estimating common business scenarios (such as ECC, BW, CRM, etc.). It aims to simplify and accelerate the process of sizing SAP applications.

By using Quick Sizer, you can efficiently convert business requirements into technical requirements. All you need to do is complete the online questionnaire, which is based on business-centric metrics. The outcome of the sizing exercise can assist you in selecting an economically viable system that aligns with your company's objectives. This feature is particularly beneficial when creating an initial budget plan.

3. Customer Performance Test

The third model namely the Customer Performance Test is performed using customer data in a customer system. However, it is worth noting that these tests can be both time and cost-intensive.

For more information, see SAP Standard Application Benchmarks.

T-Shirt Sizing Technique

This sizing technique uses t-shirt sizes (XS, S, M, L, XL) under the assumption that having an estimate is better than none. It can be useful for the budget planning phase even when figures may not be clear, assumptions can be made and validation can occur later.

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Figure 1: T-Shirt Sizing

Now, think of these t-shirt sizes as hardware requirements where XS requires the least amount of power/memory/etc. and XL requires the most.

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Figure 2: Hardware T-Shirt Sizing Equivalent

IT-Conductor Sizing Table

To make things much easier, we came up with the IT-Conductor Sizing Table based on the T-Shirt Sizing principle to guide you in your sizing exercise.

Note: The rule of thumb is 25 systems per 4CPU 4GB. Then add 4GB memory for the next 25 systems. CPU is not usually a constraint.

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