Building the Data Warehouse

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■■ DASD consumption

■■ Software requirements (including system software, utilities, special custom code, network software, interface software)

■■ CPU consumption ■■ I/O utilization

■    Main memory requirements

■    Network/channel utilization

Not only are raw requirements analyzed, but the arrival rate of transactions, peak-period processing, patterns of processing, response time requirements, availability requirements, and mean time to failure requirements are factored in as well.

In addition, if any hardware/software must be ordered, the lead time and the “burn in” time must be accounted for to ensure that proper resources will be in place in time for the application being reviewed.

The output of this phase of development is the assurance that the resources needed to be in place are, in fact, in place.

PARAMETERS OF SUCCESS: No surprises when it comes to resources being in place when needed, the lead time needed to acquire resources, and the amount of resources needed.

PREQI—Technical Environment Definition

PRECEDING ACTIVITY: Establishment of the information processing environment.

FOLLOWING ACTIVITY: Sizing, phasing.



SPECIAL CONSIDERATIONS: On occasion, it is necessary to build an application system from scratch, including defining the technical environment. If this is the case, the considerations of technical definition are outside the boundaries of the data-driven development methodology.

In order to proceed, it is necessary that the technical environment be defined. If the technical environment is not defined at this point, the result will be much “thrashing.” Simply stated, detailed design cannot be meaningfully done until the technical environment is defined.

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