Pin Read Hits is the percentage of pin read requests that hit the file system cache, i.e., did not require a disk read in ...

Pin Read Hits is the percentage of pin read requests that hit the file system cache, i.e., did not require a disk read in order to provide access to the page in the file system cache.  While pinned, a page's physical address in the file system cache will not be altered.  The LAN Redirector uses this method for retrieving data from the cache, as does the LAN Server for small transfers.  This is usually the method used by the disk file systems as well.