ES isn't really meant to be used as an operational datastore (although I appreciate some do use it that way). CouchDB provides strong durability and master-master replication. It's also very easy to sync changes from CouchDB (https://github.com/elasticsearch/elasticsearch-river-couchdb) to ES so they make a good complimentary pair. Use CouchDB for the raw data (where you want strong durability and write scalability) and use ES to search over it.