Preservation means following procedures to keep data files for an extended period of time by choosing durable formats, archiving files locally, and/or submitting data files to a data repository.
Illinois Data Bank Preservation Policy
For an example of a preservation policy, you can review the policy established for our institutional data repository, here at the University of Illinois.
Data preservation refers to maintaining access to data and files over time. For data to be preserved, at minimum, it must be stored in a secure location, stored across multiple locations, and saved in file formats that will likely have the greatest utility in the future:
Source: http://www.library.illinois.edu/sc/services/data_management/file_formats.html
Data preservation may seem like a lot of work, but there’s good news! A lot of institutions run data repositories, which support the preservation and discovery of research data. Find out if your discipline has a data repository, and check out the Illinois Data Bank where many researchers on campus have preserved and shared their data. This isn’t a complete list, so be sure to check with your subject librarian for more help.