"Speaking very broadly, with 4K scans of color films you wind up in the neighborhood of 128 MB per frame… . Figure that a typical motion picture has about 160,000 frames, and you wind up with around 24 TB per film. And that’s just the raw data. Now you process it to do things like removing dust, tears, and other digital restoration work. Each of those develops additional data streams and data files. We’ve decided, based upon our previous experience, that it is best to save the initial scans as well as the final processed files for the long term. Now we are up to 48 TB per film. In our nitrate collection alone, we have well over 30,000 titles. 48 TB x 30,000 = 1,440,000 TB or 1.44 EB (exabytes) of data. And of course you want to have a backup copy."
Ken Weissman of the Library of Congress as quoted by David Bordwell in an article exploring the monetary as well as cultural cost of archiving, restoring and preserving film.