When I was there Google used multiple Sun/StorageTek tape libraries at each datacenter. The robots handled much of it, but there was still a lot of manual tape loading and unloading performed by technicians. Once tapes were full they were unloaded and hauled off to a secure third-party facility.
They're still sold by Oracle, as far as I can tell: https://www.oracle.com/storage/tape-storage/#rc30p5
Would love some more insight on this! Anything or any article you can share on how this is implemented at such scale?