I am running Mongodb pod in kunernetes cluster using nfs volume.I am writing pod.yml like this

Putting mongo in the command: is erroneous. The daemon is mongod and the image would have started it automatically had you not provided any command: at all.

Further, all command: lines are exec-ed, so putting bash -c in front of a command is just moving that command out of pid 1 and unnecessarily adding memory consumption to your container.