ABSTRACT
The world produces more than 12 exabytes (12 billion gigabytes or 12 × 1018 bytes) of information eachsa year of which over 90% is stored on magnetic media including magnetic tape, automated tape, disk and virtual storage (defined in the entry body). Since the advent of the modern electronic computer, there have been rapid improvements in storage technologies. Each new generation of data storage has been smaller in relative size and larger in capacity. Tape cartridges and disk drives are commonly available in capacities of 3/4 to 1 terabyte (750 gigabytes to 1000 gigabytes). A three-tiered storage hierarchy can be useful for managing data storage with policies based on the importance of the data and performance, accessibility, and/or equipment/media reliability requirements. Information Lifecycle Management (ILM) is based on the notion that the lifecycle of information can be managed using various digital technologies and can be implemented using a hierarchy of those storage technologies. There currently exists no digital media that allow 100-year digital preservation. This is partly due to the inevitable obsolescence of data storage. Archival preservation of digital content requires aggressive management to ensure that content is accessible and usable. In many cases this requires backup to reliable technology and protection against unplanned modification or deletion of the files. The LOCKSS (Lots Of Copies Keeps Stuff Safe) program is one method of providing this protection. The Open Archival Information System (OAIS) framework or reference model describes the environment in which OAIS operates, the functions or services used to archive and make available the archival data, and the objects that go through the archival process.
