Storage
Scanned documents consume a good deal of storage with a monochrome image averaging 40k, and colour images five to 10 times that. In addition there is the need to ensure that documents are secure and meet the correct standards for legal admissibility. The main options are hard disk, hard disk array and CD/DVD.
The capacity of hard disks has increased rapidly and can accommodate many images. However, it is a vulnerable medium. At some point it will fail. Data can become corrupted, be too easily deleted, and is open to casual inspection. Used alone, this is the least satisfactory medium for legal purposes and needs a good backup regime to avoid loss.
A hard disk array is a configuration of hard disks arranged in such a fashion that the failure of a single disk will not result in the loss of data. These are known by a number of acronyms including RAID, SAN and NAS see Glossary.
This arrangement is clearly more robust, and as it is frequently under the control of the IT department, should be more secure. Many larger organisations rely on this method of storage and, with appropriate procedures, it is better at demonstrating the legal standing of stored documents.
CD/DVD is an extremely handy and portable medium to store information. However, it is vulnerable to damage, theft, and degrades over time. As a result it is not recommended for long-term storage. If write-once media is used, then it has the merit that once burnt, it cannot be altered. This meets an important test of legal admissibility.
Should the most robust records storage technology be required then magneto optical (MO) should be the choice. Most users will select the write-once media as it offers the highest level of integrity. It offers high capacities, particularly when configured in a jukebox; cannot be affected by magnetic forces that would destroy a hard disk, and is certified to be good for decades.
The information is written to the optical platters in the same way as on a hard disk. However, this can only happen at very high temperatures achieved by a highly focused laser beam. At lower temperatures the media is completely stable, and cannot be altered.