Research into the life-span of both magnetic and optical media has been conducted. The overwhelming conclusion from this research is that even though magnetic media can be safe for 5-10 years and optical media may survive as long as 30, technology changes much more quickly. Digital media are far more likely to become unreadable as a result of changing technology than they are through media degradation. These diskettes are completely unreadable by PC machines, and can only be accessed on networked Amstrad computers - very rare indeed in 1998. If archaeologists had refreshed their data from 3 inch Amstrad diskettes to 5.25 inch diskettes and then to 3.5 inch diskettes, these digital data would still be easily accessible and safe.
Data migration is even more important than data refreshment for successful digital archiving.
Migration is the act of copying digital information from one format or structure into another. Even though CAD packages allow data to be exported in a 'standard' format called DXF, many programs in fact create DXF files in unique ways. The unwary can find that, without careful migration, much of the original information is lost when creating a new file. In order for a digital archivist to migrate digital information successfully, it is necessary to understand the structure of the data fully and how different parts relate to one another. No digital archivist can successfully preserve data that are not fully documented, including any standards used, because at every step of data migration information can be lost.