[{_id:"622c98cfc872bcb2578b97a5",username:"foo",process:[{processname:"bar",process_status:"stopped",_id:"6230c1a401c66fc025d3cb88"},{processname:"bar",process_status:"stopped",_id:"other-id"}]}]

db.collection.update({"process._id":"6230c1a401c66fc025d3cb88"},{"$set":{"process.$.process_status":"started"}})