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Less obvious is the fact that the memory used by the compression system reduces the available system memory and thus causes a corresponding increase in overall paging activity. As more primary storage is used to store compressed data, less primary storage is available to programs, causing the level of paging activity to increase, reducing the effectiveness of the compression system.
The relationship between paging activity and available memory is roughly exponential.<ref name="DENNING"/><ref name="FREEDMAN"/> This means that for a given reduction, <math>x</math>, in available memory there will be an exponential increase in paging activity on the order of <math>e^x</math>. In circumstances where memory is low and paging is fairly prevalent, any gains in available memory may be offset by a significant
For example, in order to maximize the use of the primary storage cache of compressed pages, [[Helix Software Company]]’s Hurricane 2.0 provides a user-configurable threshold that allows the rejection level for compression to be adjusted. The program would compress the first 256 to 512 bytes of a 4 KiB page and if that small region achieved the designated level of compression, the rest of the page would be compressed and then retained in a primary storage buffer, while all others would be sent to auxiliary storage through the normal paging system. The default setting for this threshold was an 8:1 compression ratio.<ref name="PCMAG-HURR-2"/>
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