From the point of view of the operating system and the database system, the client is just a key field of the application and Customizing tables. Performances depends solely on the following:

• How many users are active in the system
• The activities of these users
• How much data is being addressed, and its distribution in the physical memory

The database resources and hardware performance required is derived from the information above, and not from the number of clients. When you size the database, calculate an initial volume of between 1 and 4 GB of Customizing data for each client, depending on the mySAP.com components you have installed.

The number of clients does, however, have direct influence on the following two aspects, and must be taken into account.

• R/3 Upgrade
  More clients lead to longer runtimes.
• R/3 Buffer
  More clients use more main memory (buffer demand), since the client is mapped in the buffer directory structure. This affects both buffer types: Keyrange Buffer and Single Record Buffer. The amount of extra memory needed varies hugely of course from case to case. We recommend a guideline of 10 MB for each client.