2.1.5+Identify+the+need+for+persistent+storage

Persistent storage is extremely vital in computer systems. This is because if all data was volatile we wouldn't be able permanently keep data for later use, as it would all be gone once we turned off the system. Persistent storage is necessary in order to be able to keep all our files and data for later use. For example a hard disk drive is an example of persistent storage, it allows us to permenantly store a variety of data. You can see how a hard disk drive works below:

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 * HDD (Hard Disk Drive)**
 * Hard-drives have a very large storage capacity (up to 1TB).
 * They can be used to store vast amounts of data. Hard-drives are random access devices and can be used to store all types of films, including huge files such as movies.
 * Data access speeds are fast but nowhere near as fast as primary memory, and this data is stored inside a hard-drive on rotating metal or glass discs (called ‘platters’).




 * Flash Memory **
 * Flash memory is a type of Electronically-Erasable Programmable Read-Only Memory (EEPROM).
 * Non-volatile (like ROM) but the data stored in it can also be erased or changed (like RAM).


 * U sing system images is the simplest persistence technology. Notebook hibernation is an example of orthogonal persistence using a system image because it does not require any actions by the programs running on the machine.**

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