Storage media can be classified on the fol properties:

■ Speed with which data can be accessed

■ Cost per unit of data

■ Reliability

● data loss on power failure or system crash

● physical failure of the storage device

■ Can differentiate storage into:

● volatile storage: loses contents when power is switched off

● non-volatile storage: ! Contents persist even when power is switched off. ! Includes secondary and tertiary storage, as well as battery backed up main-memory.