LOCKSS = Lots of Copies Keep Stuff Safe [...]

How does a digital library work? LOCKSS is one way, started in 1998 based on the OAIS Reference Model (Open Archival Information System).

The LOCKSS Program is an open-source, library-led digital preservation system built on the principle that “lots of copies keep stuff safe.” The LOCKSS system is the first and only mechanism to apply the traditional purchase-and-own library model to electronic materials.

Preservation requires three actions: a publisher to give permission for the target content to be preserved; for a library to bring online a LOCKSS box that has authorized access to the content; and for that LOCKSS box to be registered with one of a number of associated LOCKSS Alliance networks.[…]

Specifically, a LOCKSS Box performs five main functions:
It ingests content from target websites using a web crawler similar to those used by search engines.
It preserves content by continually comparing the content it has collected with the same content collected by other LOCKSS Boxes, and repairing any differences.
It delivers authoritative content to readers by acting as a web proxy, cache or via Metadata resolvers when the publisher’s website is not available.
It provides management through a web interface that allows librarians to select new content for preservation, monitor the content being preserved and control access to the preserved content.
It dynamically migrates content to new formats as needed for display [on-the-fly].

LOCKSS Website at Stanford