Secondary storage (1.2.2) GapFill

It is important for a computer to be able to store data for a long time, even when it is not in use.

 Solid-state storageCloud storageRemovable storageRAM is unsuitable for this type of storage because it  is random-accessis volatileis optical storagecannot be written to, and ROM is not enough on its own because it  is optical storageis solid-state storagecannot be written tois volatile. Instead, various different types of  main memorysecondary storagecloud storagevirtual memory are often used as the main form of long-term storage for a computer.

 Cache memory locationsUSB drivesSSDsHDDs are a type of secondary storage with moving parts. They store data by using  a reflective diska magnetised diskROMthe CPU, and are widely used in PCs because they  use less energy than any other type of secondary storagecan store a lot of data for a low costhave the highest data transfer speeds of any type of secondary storagenever corrupt data.

 Blu-ray discsDVDsSSDsCDs are also often used as a secondary storage device in PCs. They have higher data transfer rates, but are  not as durablemore expensive per GBmore prone to data corruptionnot random access.  Solid-stateCacheOpticalROM storage is mainly used for removable storage, such as CDs, which have a maximum capacity of  2GB1,000,000B700MB8b, and  Blu-ray discsSSDsDVDsHDDs, which have a maximum capacity of approximately 4.7GB (if they only use one layer).