Gathering performance information: External design phase

During the external design phase, you should:

  1. Estimate the network, processor, and DASD loading based on the dialog between users and tasks (that is, the input to each transaction, and consequent output).
  2. Revise your disk access estimates. After external design, only the logical data accesses are defined (for example, EXEC CICS READ).
  3. Estimate coupling facility resources usage for the MVS™ system logger and resource files, or any cross-system coupling facility (XCF) activity.

Remember that, after the system has been brought into service, no amount of tuning can compensate for poor initial design.

Related tasks
Gathering performance information: Requirements definition phase
Gathering performance information: Internal design phase
Gathering performance information: Coding and testing phase
Gathering performance information: Post-development review
Gathering performance information: Information supplied by end users
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