David S. H. Rosenthal
Chief Scientist, LOCKSS Program
20 years ago, Jeff Rothenberg’s seminal “Ensuring the Longevity of Digital Documents” compared migration and emulation as strategies for digital preservation, strongly favoring emulation. Emulation was already a long-established technology; as Rothenberg wrote, Apple was using it as the basis for their transition from the Motorola 68K to the PowerPC. Despite this, the strategy of almost all digital preservation systems since has been migration. Why was this? Preservation systems using emulation have recently been deployed for public use by the Internet Archive and the Rhizome Project, and for restricted use by the Olive Archive at Carnegie-Mellon and others. What are the advantages and limitations of current emulation technology, and what are the barriers to more general adoption?