2. Storage devices and media

Secondary Storage Device

A secondary storage device is the physical hardware that carries out the storage action. For instance a DVD writer is a 'storage device'.

A hard disk or a Solid State Drive are secondary storage devices.

Storage Media

Some storage devices come with removable media. For example a DVD writer burns a blank DVD. The DVD itself is an example of storage media.

Storage media is the physical object used to actually store the data.

Another storage media example is a magnetic tape cartridge. This is loaded into the magnetic tape recorder / reader (the storage device). The storage media can be removed and kept somewhere else for safe-keeping.

Some secondary storage devices do not have separate media. For example a hard disk or a Solid State Drive are self-contained with no external media.

Backup and Archiving

Both backup and archiving do the same thing - they store data.

However they do so for different reasons. A backup is created as a precaution against losing current or recent data. For example should a hard disk fail, then hopefully there is a backup copy of the data stored on another drive. Speed and ease of access is important when selecting a backup medium, for example an external hard disk is fast and can hold a large amount of data.

Archiving on the other hand is intended to free up space by storing away data that will not be needed very often. The original data is deleted. Therefore with archiving, speed of access is not important, but data capacity and the longevity of the media is very important, magnetic tape is often used as an archive medium. It has huge capacity, good longevity, cheap per Gb but is very slow. To increase capacity even further, compression is used.