having one or more of the following benefits every block io request is characterized or analyzed to understand its importance relative to other components within the virtual machines file system characterization of block io requests allows the cache to maintain a higher quality of content in the face of numerous io requests from virtual machines that would fragment a non content aware cache the characterization allows a score to be assigned to the requested block and use of the assigned score to evaluate the importance of the block in the event of a cache slot replacement scenario consequently cached blocks that are of higher importance in the ntfs file system are more resistant to replacement and take precedence in the cache the cache inclusivity problem is also solved wherein when multiple hierarchical caches are working independently as would be the case in a typical virtualization scenario all the different caches though hierarchical end up including more or less the same blocks and thus are not affective due to the content awareness of the application the cache is able to store a more diverse set of blocks than typical cache replacement mechanisms such as least recently used lru or least frequently used lfu the cache is near line to the vms thus allowing most io requests to be serviced by the caching application rather than the san nas system and thus offloading the san nas from contention allowing for performance and response time benefits embodiments of the present invention pertain to the methods and systems to increase cache efficacy and to.