意外重启后，mongodb无法链接，stop服务时提示"stop: Unknown instance"

Question

ubuntu系统，早上启动不起来。只好复位键强行重启后，执行

>> sudo service mongodb start
mongodb start/running, process 1059

但是发现无法链接，然后执行

>> sudo service mongodb stop
stop: Unknown instance

搞不懂了，怎么办？

Answer 1

Try deleting the mongo.lock file in the data folder and restarting

Answer 2

Check if mongdb is indeed running, if so it can be used

sudo mongod --shutdown --dbpath <PATH_TO_DB>

Answer 3

It should be caused by abnormal shutdown.
linux:
sudo top, check to see if there is a process running mongo. If so, kill it and try starting mongo.