I am trying to create a new folder in the main directory

Tried all kinds of examples

sudo mkdir /data/db

sudo mkdir -p /data/db

I keep getting

mkdir: /data: Read-only file system

4

16 Answers

If you have a Mac and updated to Catalina or more recent version, then the root folder is no longer writable.

I just changed the directory somewhere else.

Been using this command for now

mongod --dbpath=/Users/user/data/db
10

from the official docs

install homebrew and run the following commands

sudo chown -R $(whoami) $(brew --prefix)/*

then

brew tap mongodb/brew

then

brew install mongodb-community@4.2

and

brew services start mongodb-community

or

mongod --config /usr/local/etc/mongod.conf

then

ps aux | grep -v grep | grep mongod

and

mongo

to verify you can run show dbs in the mongo shell

2

With the new macOS Catalina update, the folder /data/db becomes read-only, you cannot modify it. Follow this procedure to create a DB in another folder:

  1. Change mongod directory :

    sudo mongod --dbpath /System/Volumes/Data/data/db

  2. Give it an alias to use it as mongod:

    alias mongod="sudo mongod --dbpath /System/Volumes/Data/data/db"

  3. Just type mongod in your terminal, it should work.

Extra => If you need to give it current user rights, use this line of code :

sudo chown -R $(whoami) /System/Volumes/Data/data/db

(Just for info -> $(whoami) is just a variable that returns your current user)

5

To make a permanent change of the path of mongod db folder.

Following these docs they say roughly this. If mongod is started with brew services:

$ brew services start mongodb-community@4.2

It will use config file at path /usr/local/etc/mongod.conf

To fix this, edit the config file:

$ vim /usr/local/etc/mongod.conf

And change the dbPath e.g. to your home directory like this:

systemLog: destination: file path: /usr/local/var/log/mongodb/mongo.log logAppend: true storage: dbPath: /Users/<username>/data/db net: bindIp: 127.0.0.1

Save the file and restart mongod with brew:

$ brew services restart mongodb-community@4.2
2

You can't create a folder on the root directory on Mac Catalina anymore!

Dedicated system volume

macOS Catalina runs in a dedicated, read-only system volume — which means it is completely separate from all other data and helps improve the reliability of macOS.

# macOS Catalina, mkdir path $ sudo mkdir -p /System/Volumes/Data/data/db # give permissions $ sudo chown -R `id -un` /System/Volumes/Data/data/db 
# macOS 10.14.x - $ sudo mkdir -p /data/db # macOS 10.15.x + $ sudo mkdir -p /System/Volumes/Data/data/db

refs

0

So, with macOS Catalina Apple created a new Volume for security purposes. If you’re on macOS Catalina, you'll need to create the /data/db folder in System/Volumes/Data.

Follow these commands

  1. sudo mkdir -p /System/Volumes/Data/data/db
  2. sudo chown -R id -un /System/Volumes/Data/data/db

Start MongoDB

  1. brew services run mongodb-community

  2. Enjoy 😉

1

If you are on mac and facing the issue then below command is useful, whoami variable will get the current user 

mongod --dbpath=/Users/$(whoami)/data/db

I am at a loss why Apple did that.. So now, we can not have any root level directory other than theirs ? This just doesn't make any sense and people creating with root privileges those folders know what they are doing

Default Paths for the mongodb-community Formula

In addition to installing the MongoDB server and tool binaries, the mongodb-community formula creates:

  • a configuration file: /usr/local/etc/mongod.conf
  • a log directory path: /usr/local/var/log/mongodb
  • a data directory path: /usr/local/var/mongodb

then it worked for me:

mkdir -p usr/local/var/mongodb/data/db

This is what worked for me as I was undergoing a Udemy course: 1. Install HomeBrew by typing this into your terminal

/usr/bin/ruby -e "$(curl -fsSL )"

  1. Move your old /data/db folder (if you want to backup your current dbs) into a non root folder and proceed with the next step

  2. Run in Terminal a) brew uninstall mongodb b) If needed run brew uninstall --force mongodb c) brew tap mongodb/brew d) brew install mongodb-community e) brew services start mongodb/brew/mongodb-community

  3. All you need now is to run mongo in the Terminal and you'll see the mongo shell symbol >.

Please let me know if this works ;) It took me almost 2 hours to figure it out, based on this article:

Cheers, Radu

I did this:

mkdir -p usr/local/var/mongodb/data/db

since the new path that is "usr/local/var/mongodb".

To add on to what David Buck wrote here, first you have to actually make the directory. You can do that with:

sudo mkdir /System/Volumes/Data/data/db

If you're getting this error:

"Error parsing command line: unrecognised option '--dbpath/System/Volumes/Data/data/db' try 'mongod --help' for more information"

after creating the alias, it's just because David Buck (while making a really helpful comment) missed a space in his answer.

To fix this, type

unalias mongod

and then type

alias mongod="sudo mongod --dbpath /System/Volumes/Data/data/db"

1

With macOS Catalina, you can no longer store files or data in the read-only system volume, nor can you write to the "root" directory ( / ) from the command line, such as with Terminal.

You cannot create a /data/ directory. That is reserved for the APFS filesystem. Check Bombich’s blog about this issue.

2

I create a gist with simple steps to install and run mongodb on catalina

# install homebrew () and run the following commands sudo chown -R $(whoami) $(brew --prefix)/* brew tap mongodb/brew brew install mongodb-community@4.2 ## --- aliases to set in your zshrc file # open your zshrc file open ~/.zshrc # copy and paste shorcuts in the end of the file alias mongod='brew services run mongodb-community' alias mongod-start='brew services start mongodb-community' #will start MongoDB automatically when you login into your Macbook alias mongod-status='brew services list' alias mongod-stop='brew services stop mongodb-community' # restart your terminal # type mongod in your terminal for run service & mongod-stop for finish it # test your mongodb connection with mongo show dbs

Mac version Catalina made the root folder is no longer writable.

Brew has an updated version of mongodb to use a new path (which it creates itself), /usr/local/var/mongodb and following these instructions will fix the issue:

Guide to installing updated mongodb-community-edition

brew install mongodb-community@VERSION where the first VERSION with the fix is 4.2