Abstract: A cooperative disk cache management and rotational positioning optimization (RPO) method for a data storage device, such as a disk drive, makes cache decisions that decrease the total access times for all data. The cache memory provides temporary storage for data either to be written to disk or that has been read from disk. Data access times from cache are significantly lower than data access times from the storage device, and it is advantageous to store in cache data that is likely to be referenced again. For each data block that is a candidate to store in cache, a cost function is calculated and compared with analogous cost functions for data already in cache. The data having the lowest cost function is removed from cache and replaced with data having a higher cost function.