This article is from the storage FAQ part2, by Rodney D. Van Meter with numerous contributions by others.
Cray Research's Data Migration Facility. The grandaddy of Unix HSM systems. You can find info on DMF at http://www.cray.com/product-info/sw/SM/DMF_flyer.html, or call +1 612 683 3897 or email email@example.com. It's reportedly running on more than 200 systems, and development is continuing. Large users are in the hundreds of TB, with millions of files and >1TB/day through DMF. Information from: "Storage Management at Cray Research, Inc", Metcalfe, D.J. and Thompson. D. "Data Migration Facility Development Update", Lazatella, T.W. and Bannister, N. Cray User Group, Barcelona, 1996, in press. (Robert.Bell@dit.csiro.au, 1996/4/2)