This article is from the storage FAQ part2, by Rodney D. Van Meter with numerous contributions by others.
Storage Tek makes huge autochangers, referred to as silos, round and several (~5) meters in diameter. They hold 6,000 3480-style tapes. At original 3480 densities, that's only 1.2 TB per silo, but capacities have gone up to (I think) 800 MB/cartridge, and are poised for a HUGE jump if Storage Tek gets their Redwood tape drive finished (in beta test, 12/94), up to 20 GB/cartridge, 120 TB/silo. There is a smaller silo, known as WolfCreek, that holds 500-1000 cartridges. STK also OEMs a 3480 autochanger from Odetics. Holds ~260 cartridges, I think, in rotating drum, with room for ?2? tape drives above it. (rdv,95/1/12) However, I couldn't find any info about this on the web site. They also have a web site at http://www.stortek.com. (95/5/16,rdv) All but the Odetics (known as Ocean, I think) are Redwood-compatible. The new 9710 (codenamed Panther) can handle both DLT and 3480 cartridges in a mini-tower. (email@example.com, 1996/3/12)