Storage Structure Volatile storage: Does not survive system crashes Examples:main memory,cache memory Nonvolatile storage: Survives system crashes Examples:disk,tape,flash memory,non-volatile RAM But may still fail,losing data ■Stable storage: A mythical form of storage that survives all failures Approximated by maintaining multiple copies on distinct nonvolatile media See book for more details on how to implement stable storage Database System Concepts-7th Edition 19.5 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 19.5 ©Silberschatz, Korth and Sudarshan th Edition Storage Structure ▪ Volatile storage: • Does not survive system crashes • Examples: main memory, cache memory ▪ Nonvolatile storage: • Survives system crashes • Examples: disk, tape, flash memory, non-volatile RAM • But may still fail, losing data ▪ Stable storage: • A mythical form of storage that survives all failures • Approximated by maintaining multiple copies on distinct nonvolatile media • See book for more details on how to implement stable storage