Tengo el mismo error contigo, este es mi caso:
~# mongod
2018-07-15T05:27:08.265+0000 I JOURNAL [initandlisten] journal dir=/data/db/journal
2018-07-15T05:27:08.265+0000 I JOURNAL [initandlisten] recover : no journal files present, no recovery needed
2018-07-15T05:27:08.301+0000 I JOURNAL [durability] Durability thread started
2018-07-15T05:27:08.301+0000 I JOURNAL [journal writer] Journal writer thread started
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] MongoDB starting : pid=26796 port=27017 dbpath=/data/db 64-bit host=ubuntu-s-2vcpu-4gb-sfo2-01
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten]
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten]
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] ** We suggest setting it to 'never'
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten]
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] db version v3.0.6
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] git version: 1ef45a23a4c5e3480ac919b28afcba3c615488f2
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] build info: Linux build6.ny.cbi.10gen.cc 2.6.32-431.3.1.el6.x86_64 #1 SMP Fri Jan 3 21:39:27 UTC 2014 x86_64 BOOST_LIB_VERSION=1_49
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] allocator: tcmalloc
2018-07-15T05:27:08.302+0000 I CONTROL [initandlisten] options: {}
2018-07-15T05:27:08.308+0000 I NETWORK [initandlisten] waiting for connections on port 27017
Escribo mongod para iniciar el servidor y escribo control
+c
para salir al shell
luego escribo mongo
y tengo
~# mongo
MongoDB shell version: 3.0.6
connecting to: test
2018-07-15T05:05:02.738+0000 W NETWORK Failed to connect to 127.0.0.1:27017, reason: errno:111 Connection refused
2018-07-15T05:05:02.739+0000 E QUERY Error: couldn't connect to server 127.0.0.1:27017 (127.0.0.1), connection attempt failed
at connect (src/mongo/shell/mongo.js:179:14)
at (connect):1:6 at src/mongo/shell/mongo.js:179
Como puede ver, mi información de error es la misma que la suya.
Este es el caso de que mongod no comience con el proceso de backend, cuando escribo control
+ c
salgo de mongod.
Podemos agregar --fork args para hacer que el demonio de proceso se procese.
# mongod --logpath /usr/local/mongodb/log.txt --fork
tienes que establecer --logpath si quieres usar --fork
entonces tendrás éxito para conectarte a mongo
mongod
el servidor no se está ejecutando, enciéndalo escribiendomongod
en la terminal.