8.1.11 Testing Equipment
8.1.11.1 Professional testing equipment with dedicated, or at least specified, drives is recommended for accurate testing DVDs and CDs. Such systems are more expensive but are necessary if accurate, reliable and repeatable error measurement are to be achieved. The testing should at least comply with ISO 12142 Electronic imaging – Media error monitoring and reporting techniques for verification of stored data on optical digital data discs. Such testing will not, however, address the problem of the lack of standardisation of optical disc drives. There is at the moment of writing, a standards project with the International Standards Organisation, ISO N178 Electronic imaging – Classification and verification of information stored on optical media, which may address the specific problem of drive compatibility. Although there is test software available on the web as shareware, such software should be carefully evaluated before being relied on in an archival environment. Such software based systems depend on the accuracy of the non-standard computer drives. If a testing system based on computer drives is required, then a proprietary system supplied by the disc manufacturer stands a better chance of being useful. At least one CD/DVD burner company does provide software that allows their drive to be used for the purposes of testing. The results of any testing system that depends on the CD burning drive should be checked against a known, calibrated testing system to ensure adequate compliance.
8.1.11.2 Disc test equipment which accurately measures only the parameters specified in this guidance document are commercially available and of good standard. However, the figures provided by testing these parameters are suitable only for identifying problems. Analysis of problems probably requires access to a high analytical CD and DVD testing facility. It is useful to gain access to this type of equipment, by renting or borrowing, when solving problems, selecting blank media or calibrating in house testing facilities.
8.1.11.3 Kodak, in their web-document “Permanence and Handling of CDs” (Kodak 2002) claim that 95 % of their CD- Rs will maintain a data lifetime of a hundred years in an office environment. The results of these tests are often held to be suspect by archivists, and many have found it difficult to reproduce the tests and achieve the same results. This may be due to different interpretation of the figures and some argument about the validity of the method of estimating lifespan. Even if these tests proved to be true, and in the unlikely event that CD drives are still available 100 years hence, a 5% failure rate is unacceptable in an archive. This conclusion also supports the requirement of an error monitoring program.
8.1.11.4 Accurate, High Quality Production Testers
8.1.11.4.1 At the time of writing the cost of accurate, high quality production testers starts at around US$ 30,000 for the basic models and increases to over US$ 50,000 for many devices. The cost is incurred in the high quality reference drives which are a necessity for accurate and repeatable testing. All testers are aimed at the market of optical disc manufacturers for production control purposes. Actual prices depend on the scale of measurable parameters, many of which are not relevant for testing recordable optical discs as to their archival reliability. Currently, there are three producers of high quality testers:Audio Development (http://www.audiodev.com/), DaTARIUS (http://www.datarius.com/) and Expert Magnetic Corporation (http://www.expertmg.co.jp/). Manufacturers and suppliers should be contacted for quotes.
8.1.11.5 Mid Range Quality Production Testers
8.1.11.5.1 At the time of writing the cost of these devices range from a US$ 3,000 to US$ 11,000 or more. These systems test all the required parameters using standard PC drives which have been specially selected and calibrated. It is recommended that before considering such mid priced testers, the prospective purchaser investigate thoroughly the types of drives and the accuracy of the device. It is also strongly recommended that all mid priced systems be regularly calibrated against a known standard. Currently, a major manufacturer of such mid range testers is Clover Systems (http://www.cloversystems.com/)
8.1.11.6 Downloadable Testers
8.1.11.6.1 There are a number of downloadable testers available online which use a computer’s inbuilt CD/DVD drive to measure error in written CD and DVDs. However, due to the limitations of the software and inaccuracy of the drives, most, if not all, are unsuitable for archival purposes.
