1. A method for managing a memory subsystem in a computer system, the memory subsystem including a secondary memory, a cache memory and memory subsystem control apparatus, said method being for use in response to a plurality of cache hit data write accesses each occurring at a different access time, said method comprising the steps of, in response to each given one of said cache hit data write accesses: determining whether said memory subsystem is, at the time of said given write access, in a first state in which said control apparatus can write the data of said given write access to said secondary memory within a first length of time after the time of said given write access, or in a second state in which said control apparatus requires longer than said first length of time to write the data of said given write access to said secondary memory, said memory subsystem being in said first state for some of said write accesses and in said second state for others of said write accesses; writing the data of said given write access to said memory subsystem using a first cache write policy if said memory subsystem is in said first state at the time of said given write access; and writing the data of said given write access to said memory subsystem using a second cache write policy if said memory subsystem is in said second state at the time of said given write access.