we don't use any replication, Also in almost 5 years we only had one server crash which was due to file-system corruption, and we overcome that as well, it was a few leveldb files which got corrupt due to which the whole XFS file-system was went down, but we recovered it. Just one drawback was: We never used the same filer for saving files, and Get speed was also quite slow on that one, but with time, the volume compaction and vacuum, everything works fine on GET requests.