Aspects provide a method of determining a storage location for a data item, including providing first and second data storage locations, the first location having an appreciably faster access speed than the second, the data storage locations are primary storage locations providing persistent storage, accessing a score associated with the data item, the score being calculated based on a frequency of access; and selecting only one of the storage locations based on the score with respect to other data scores, wherein the data item is stored in only one of the storage locations at any time, re-calculating the scores, wherein the score is accessed from a score table of data items; and in response to re-calculating of the scores, causing a change in the selection of the data storage location, removing the data item from a current storage location and adding the data item to a newly selected storage location.