1. An apparatus comprising a storage array, a cache memory coupled to a host device, and first means for establishing a flushing list in the cache memory which respectively associates a predetermined maximum number of sets of writeback data in the cache memory to each of a plurality of locations in the storage array, for executing a read command from the host device to transfer a readback data set from a selected location of the storage array in conjunction with execution of at least one pending write command to transfer an associated writeback data set to the selected location in relation to a monitored rate at which additional sets of writeback data sets are transferred to the cache memory from the host device, for backfilling the flushing list to associate at least one of the additional sets of writeback data with the selected location to maintain said predetermined maximum number of writeback data sets for said selected location, and for adjusting the predetermined maximum number of writeback data sets for said selected location over time in relation to burst changes in a read/write command mix experienced by the first means.