我删除了 MongoDB 2.6 并安装了 MongoDB 3.4。当我连接到 MongoDB 3.4 服务器时，有几个新的启动警告：
MongoDB shell version v3.4.2
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.2
Server has startup warnings:
2017-03-20T20:27:36.175+0545 I STORAGE [initandlisten]
2017-03-20T20:27:36.175+0545 I STORAGE [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2017-03-20T20:27:36.175+0545 I STORAGE [initandlisten] ** See http://dochub.mongodb.org/core/prodnotes-filesystem
2017-03-20T20:27:36.855+0545 I CONTROL [initandlisten]
2017-03-20T20:27:36.855+0545 I CONTROL [initandlisten] ** WARNING: Access control is not enabled for the database.
2017-03-20T20:27:36.855+0545 I CONTROL [initandlisten] ** Read and write access …mongodb ×1