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Computer Resource Requirements

There is no inherent limit on the size of the project that can be scheduled with the CPM procedure. The number of activities and precedences, as well as the number of resources are constrained only by the amount of memory available. Naturally, there needs to be a sufficient amount of core memory available in order to invoke and initialize the SAS system. As far as possible, the procedure attempts to store all the data in core memory.

However, if the problem is too large to fit in core memory, the procedure resorts to the use of utility data sets and swaps between core memory and utility data sets as necessary, unless the NOUTIL option is specified. The procedure uses the NACTS=, NADJ=, NNODES=, and NRESREQ= options to determine approximate problem size. If these options are not specified, the procedure estimates default values on the basis of the number of observations in the Activity data set. See the section "Syntax: CPM Procedure" for default specifications.

The storage requirement for the data area required by the procedure is proportional to the number of activities and precedence constraints in the project and depends on the number of resources required by each activity. The time required depends heavily on the number of resources that are constrained and on how tightly constrained they are.