If you get this warning when you connect to mongo shell in Mac OX X:
** WARNING: soft rlimits too low. Number of files is 256, should be at least 1000
A simple way to fix this is setting the limit just before starting mongod with this:
ulimit -n 1024 && mongod
Or this:
launchctl limit maxfiles 1024 1024
But if you are running mongo in a development environment this shouldn’t be a problem, you can just ignore it.
This is a temporary and not very pretty fix. To make this permanent you have to add this to the/etc/launchd.conf file:
launchctl limit maxfiles 1024 1024
Now reboot to make changes effective.
You can see the actual values of the limits running this:
$ launchctl limit maxfiles
maxfiles 1024 1024
Remember to restart your mongod process every time you change any value to see if it works.