scope:

This International Standard specifies a data migration method for long-term data storage. According to the standard, manufacturers are able to construct storage systems that use DVD-R, DVD-RW, DVD-RAM, +R, or +RW disks for information storage. A user of the storage system can select disks with sufficient longevity potential, on the basis of an initial performance test, and can continuously monitor the potential for retrieving data from those disks on the basis of periodic performance test. These tests are to establish a practical estimate of the retrievability of the recorded data on a disk without producing uncorrectable errors, in response to time at controlled storage conditions to produce accelerated aging. Digital data can be migrated to a next new disk without loss from the present disk as long as data errors are completely corrected before and during the migration, and provided copying of the data is allowed.

The methodology for data migration is intended to be applied to disks with longer storage lifetime. It is recommended to use disks with estimated life time is given as a mean value and a standard deviation as specified in ISO/IEC 16963. If the estimated lifetime of the disks is known, users can determine a test interval according to the estimated lifetime. If the estimated lifetime is known as a mean value and a standard deviation, regardless of the test method for the estimation, it is recommended to carry out data migration based on this standard. If the estimated lifetime is unknown, the test interval should be three years or less. Considering the generational changeover of systems or applications, the user can determine a migration interval disregarding the estimated lifetime of the disks.

Disks with shorter estimated lifetimes have more rapid degradation and require more frequent periodic tests. In addition, degradation of recorded data occurs by complex failure mechanisms. Storage lifetime, therefore, varies depending not only on temperature and humidity but also on many other effects such as exposure to light, corrosive gases, contamination, handling, and variation in playback subsystems. Consequently, severe storage environments require more frequent periodic tests. The frequency of periodic testing also needs to be fixed based on the quality of the disks for storing data and the storage environment.