Migration vs. Emulation in Digital Preservation

Digital records face a slow threat: the formats and software they depend on become obsolete. Two core digital preservation strategies address it from opposite directions — migration and emulation.

Migration

Migration keeps records usable by converting them to current formats over time. As an old format heads toward obsolescence, you migrate the records to a newer, well-supported preservation format, repeating as technology evolves.

Strengths: records stay usable with today’s everyday tools; straightforward for common document and image formats.
Risks: each conversion can introduce loss or change — formatting, functionality, or subtle fidelity. Migrations must be validated, and the cumulative effect tracked.
Best for: the bulk of records, especially documents and images in standard formats.

Emulation

Emulation keeps the original files unchanged and instead recreates the environment needed to use them — running old software (and, via emulators, old operating systems) on current hardware so the original record behaves as it did.

Strengths: preserves the original exactly, including complex behavior, interactivity, and look-and-feel; avoids conversion loss.
Risks: technically complex to set up and sustain; depends on maintaining or recreating old software, with its own legal and technical hurdles.
Best for: complex or interactive material (software, databases, multimedia) where conversion would lose essential character.

They’re complementary

This isn’t strictly either/or. Many preservation programs migrate the bulk of straightforward records while reserving emulation for complex objects that migration can’t faithfully handle. Both rely on the same supporting practices: rich preservation metadata, fixity checks, and redundant storage.

The takeaway

Migration converts the record to fit current technology; emulation recreates old technology to fit the record. Choose by material type and fidelity needs — and remember both are ongoing commitments, not one-time fixes. Keeping digital records usable for decades is active work, not passive storage. See the vital records, archives and preservation hub for more.