storage hierarchy - a hierarchy of storage technologies used to implement data storage, with smaller amounts of faster and more expensive memory at the top of the hierarchy and larger amounts of slower, less expensive memory at lower levels;
дс тдрлими цюлютдажкию дроемжки аиакиохдйис лидр
http://www.harcourt.com/dictionary/def/9/8/7/4/9874800.html;
