Storage Hierarchy (Cont.) primary storage:Fastest media but volatile (cache,main memory). secondary storage:next level in hierarchy,non-volatile, moderately fast access time also called on-line storage E.g.flash memory,magnetic disks tertiary storage:lowest level in hierarchy,non-volatile,slow access time also called off-line storage E.g.magnetic tape,optical storage Database System Concepts-5th Edition,Oct 23,2005. 11.10 ©Silberschat乜，Korth and SudarshanDatabase System Concepts - 5 11.10 ©Silberschatz, Korth and Sudarshan th Edition, Oct 23, 2005. Storage Hierarchy (Cont.) primary storage: Fastest media but volatile (cache, main memory). secondary storage: next level in hierarchy, non-volatile, moderately fast access time also called on-line storage E.g. flash memory, magnetic disks tertiary storage: lowest level in hierarchy, non-volatile, slow access time also called off-line storage E.g. magnetic tape, optical storage