The Aeternity Blockchain has been using mnesia with the mnesia_rocksdb backend plugin since it went live in 2017, and now handles a 100 GB database. At the Functional Conf 2022 Ulf is speaking about his experiences and presents an evolution of the mnesia_rocksdb plugin, see
https://dev.confengine.com/conferences/functional-conf-2022/speaker/interview/ulf-wiger