White paper - Alternative Storage Technologies

Alternative Storage Technologies Whitepaper

MICROFILM What it is: Microfilm is 16mm or 35mm film stored on open reels or in cassettes. It contains small images, usually in black and white, although some microfilm formats also support digital data. The two main types of microfilms are: • Silver halide film: The recommended alternative for long-term preservation. The image is trans- ferred to the film by using silver emulsion on a polyester strip. • Vesicular film: Creates the image on the polyester strip by using microscopic bubbles instead of silver emulsion, making it a less expensive but also a less durable solution. Special cameras capable of photographing at reduced size are used in order to transfer an image to microfilm. The image is then printed on the film and chemically processed in a laboratory. The film processing makes the recording process more complex compared with some of the alter- native technologies. In spite of this, microfilm is widely used for long-term preservation of data, for a number of reasons. Long durability and no need for decoding: Microfilm has a lifetime expectancy of up to several hundred years when stored properly at the recommended temperature and humidity levels. Additionally, as the data is normally analogue, data stored on microfilm can be read back by simply using a magnifying glass. Hence data retrieval is independent of specific reading devices, and the images on the film require no software decoding. Desktop readers with large screens and zooming lenses are normally used for data retrieval. The downside is that it is a manual and cumbersome process to access and reproduce data stored on traditional microfilm. Amigration-freeWORM: Thedurability and secure read-back of information written as images make microfilm a migration-free storage alternative, potentially creating large cost savings and elim- inating the risk of migration-related data loss. By being an analogue medium stored offline, micro-

A microfiche has many of the same attributes as microfilm, but is formatted as a card rather than as a film reel. They are normally stored in open top envelopes in drawers or boxes. An ultrafiche is a compact version of a microfiche, storing images at much higher densities and often made directly from computers.

film is also a secure solution. As a true WORM (Write Once, Read Many) it is literally impossible to edit or delete the information that is written to the film. Hence microfilmmeet many of the criteria for long-term preservation. Manual handling: The major drawback with micro- film is that the workflow for reproducing data is time-consuming and largely manual. Microfilm was designed for storing analogue images, and in a world overflowing with digital data, traditional microfilm is simply not an efficient alternative.

Microfilm reader