A system and method for defining retention and lifecycle policies for data backups. A media server supports a recovery-chain-based retention policy for data lifecycle management (DLM) on a first tier of a multi-tier storage system. A recovery chain includes full backup data and at least one partial backup data. The recovery chain is maintained on the first tier until it is expired due to a new full backup operation being performed and corresponding full backup data being stored on the first tier. Based on another retention policy, the media server identifies given backup data corresponding to a recovery chain that qualifies for migration from the first tier. However, the media server determines the recovery chain includes the given backup data and other backup data that does not yet qualify for migration. In response, the media server maintains a copy of the given backup data on the first tier.