ulimit hell.

ulimitconfs.sh

# /etc/security/limits.conf
root - nofile 65000
deployer - nofile 65000

# Ubuntu upstart file at /etc/init/mongodb.conf
start on runlevel [2345]
stop on runlevel [016]
respawn

script
  ulimit -n 65000
  exec su - root -c "/etc/mongodb/bin/mongod --port '27017' --dbpath '/home/deployer/mongodb/db/mongodb27017' --journal" >> '/home/deployer/mongodb/log/mongodb27017.log' 2>&1
end script

# For /etc/init.d/<script> just add the following somewhere:
ulimit -n 65000