Data retention defines the policies of persistent data and records management for meeting legal and business data archival requirements. A data retention policy weighs legal and privacy concerns against economics and need to know concerns to determine both the retention time, archival rules, data formats, and the permissible means of storage, access, and encryption.
Data retention issues plagued recovery of essential data of many early computer systems, notably the data recovery for the Viking lander.[1]
Open Rights Group's page on Data Retention