The Persistent Archive Testbed and National Archives and Records Administration (NARA) research prototype persistent archive are examples of preservation environments. Both projects are using data grids to implement data management infrastructure that can manage technology evolution. Data grids are software systems that provide persistent names to digital entities, manage data that are distributed across multiple types of storage systems, and provide support for preservation metadata. A persistent archive federates multiple data grids to provide the fault tolerance and disaster recovery mechanisms essential for long-term preservation. The capabilities of the prototype persistent archives will be presented, along with examples of how the capabilities are used to support the preservation of email, Web crawls, office products, image collections, and electronic records.