Robotic tape libraries (like the StorageTek/Sun/Oracle SL8500) are standard. However, the robotic part is not to swap parts in case of failure - instead, it is

Robotic tape libraries (like the StorageTek/Sun/Oracle SL8500) are standard. However, the robotic part is not to swap parts in case of failure - instead, it is to let ~64 tape drives access ~100k individual tapes within the library and ~inf tapes in off-site storage (as the data stored is not, and _shouldn't_ be, directly accessible).