1. A method of filtering I/O requests of a computer system, the method comprising: (a) receiving a plurality of I/O requests from a filter manager of the computer system, the filter manager executing in the system space of an operating system executing on the computer system; (b) applying a hierarchical rule set to at least a portion of the plurality of I/O requests by a mini-filter executing in the system space of the operating system executing on the computer; and (c) providing at least one of the plurality of I/O requests from the mini-filter to an agent executing in user space of the operating system in response to the application of the hierarchical rule set by the mini-filter.