PrimoCache is a supplementary software caching scheme that cooperates with system memory to provide data caching for disks. It improves system performance by transparently storing data into memory such that future requests for that data can be served faster. PrimoCache caches data on a logical block basis (offsets within a disk) while windows cache manager caches on a virtual block basis (offsets within a file). PrimoCache can also utilize the OS Invisible Memory which is wasted on 32-bit Windows when 4GB memory or more is installed.