the question with many databases using rotational based storage engines is not how much you want to store, but how much you want to query. Couch requires 99% cache hit rates for queries, they tell you to add memory if you are lower. which really makes it an in memory database with a disk based backing store, suitable for modest data sizes. i have also never seen a positive jepsen test, so i believe it is known to lose data in split brain modes.