MongoDB: exception in initAndListen: 20 Attempted to create a lock file on a read-only directory: /data/db, terminating

Question

I created /data/db in root directory and ran ./mongod:

[initandlisten] exception in initAndListen: 20 Attempted to create a lock fi         


        

Answer 1

I dealt with the same problem:

Change to the MongoDB directory which contains the bin directory, and run:

sudo bin/mongod 

Running MongoDB as the root user you might be asked to enter the root password. If you still can not run the MongoDB, then check the permissions for MongoDB's data directory. Enter:

ls -ld /data

or type ls -l / for the permissions for all directories and files in the directory including the /data directory.

The permission mode for the root user should be "rwx", meaning the root user is able to read, write and execute the files. To make this happen, we use:

chmod 755 /data 

755 is a octal notation to set the permissions, of the /data directory to "rwxr-xr-x", which means the root user can read, write and execute, whereas the "group" and "everyone"are able to only read and execute.

Note: When you can't do this, type instead:

sudo chmod 755 /data   

to set the permission as the root user.

Then, when done with that step, recapture the permission modes using:

ls -ld /data

which should look like:

drwxr-xr-x  3 root  wheel  102 Mar  3 17:00 /data

You don't need to worry about the "d" at the beginning, and notice that the permissions reflect "rwxr-xr-x".

You can now change back to the MongoDB directory and type:

sudo bin/mongod  

to run MongoDB.