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NPAGERAD is a system parameter that specifies the total number of bytes of nonpaged pool that will be allocated for Resource Affinity Domains (RADs) other than the base RAD (Alpha and Integrity only). For platforms that have no RADs, NPAGERAD is ignored. Notice that NPAGEDYN specifies the total amount of nonpaged pool for all RADs.

Also notice that the OpenVMS system might round the specified values higher to an even number of pages for each RAD, which prevents the base RAD from having too little nonpaged pool. For example, if the hardware is an AlphaServer GS160 with 4 RADs:

NPAGEDYN = 6291456 bytes 
NPAGERAD = 2097152 bytes 

In this case, the OpenVMS system allocates a total of approximately 6,291,456 bytes of nonpaged pool. Of this amount, the system divides 2,097,152 bytes among the RADs that are not the base RAD. The system then assigns the remaining 4,194,304 bytes to the base RAD. Note that the system actually rounds up to an even number of pages on each RAD. In addition, the base RAD is never assigned a value less than the smaller of the value of NPAGEDYN and 4 megabytes.

On AlphaServer GS series processors on OpenVMS systems prior to Version 7.3-1, system managers frequently saw pool expansion that increasing NPAGEDYN did not reduce. This problem was caused by leaving NPAGERAD at its default value of 0. Starting with OpenVMS Version 7.3-1, when NPAGERAD is 0 (the default), the system calculates a value to use for NPAGERAD with the following formula:

NPAGERAD = NPAGEDYN * (1-(Base RAD memory/Total memory))

This calculation gives more pool to the non-base RADs than before and, therefore, reduces the expansion of non-base RADs.

NPAGERAD has the GEN attribute.