Reads Denied/sec is the rate at which the server is unable to accommodate requests for Raw Reads. When a read is much larger ...

Reads Denied/sec is the rate at which the server is unable to accommodate requests for Raw Reads.  When a read is much larger than the server's negotiated buffer size, the Redirector requests a Raw Read which, if granted, would permit the transfer of the data without lots of protocol overhead on each packet.  To accomplish this the server must lock out other requests, so the request is denied if the server is really busy.