Expected access times (EATs) of write request to a disk drive are essentially a measure of the predicted service time for the write request. Write Requests generated by a caching storage controller to a disk drive are essentially maintenance functions used to clear the cache. The disk drive modifies the EATs of write commands with a penalty such that read requests requiring disk access are preferentially satisfied. The penalty may be constant or may be established based on one or more factors, and may even be negative if necessary to clear a cache full of writes requiring destaging to disk.