034 Configure Autofs

Tech Tutorial: Create and Configure File Systems with Autofs #

Introduction #

In this tutorial, we are going to learn about autofs, a service that automatically mounts file systems in Linux whenever a file or directory within that file system is accessed. This feature is particularly useful in managing large networks of computers, such as in a corporate environment, where network drives need to be accessed on-demand without permanently mounting them, which could consume system resources unnecessarily.

autofs is especially relevant for system administrators preparing for the Red Hat Certified System Administrator (RHCSA) exam, as it forms a critical component of the exam’s objectives under managing file systems.

Prerequisites #

  • A system running RHEL 7 or RHEL 8
  • Sudo or root access on the system
  • Basic understanding of Linux file systems and terminal usage

Step-by-Step Guide #

Step 1: Installing Autofs #

Before configuring autofs, the first step is ensuring that it is installed on your Red Hat system. Open your terminal and run the following command:

sudo yum install autofs

Step 2: Configuring Master and Map Files #

autofs uses a master configuration file, typically /etc/auto.master, to control the operation of the automounter. Map files, specified in the master file, provide detailed mount information for specific directories.

Editing the Master File #

Open the master configuration file in a text editor:

sudo vi /etc/auto.master

Add the following line to mount NFS shares:

/misc /etc/auto.misc

This line tells autofs to look in /etc/auto.misc for mount configurations whenever something in the /misc directory is accessed.

Creating the Map File #

Now, create or edit the map file mentioned in the master file:

sudo vi /etc/auto.misc

Add the following line to mount a hypothetical NFS share:

data -rw,soft,intr,rsize=8192,wsize=8192 server.example.com:/export/data

This configuration mounts the NFS share located at server.example.com:/export/data with various NFS-specific options like rw for read-write access and soft for soft-mounting.

Step 3: Starting and Enabling Autofs #

Once the configuration files are set up, start the autofs service:

sudo systemctl start autofs

To ensure autofs starts automatically at boot:

sudo systemctl enable autofs

Step 4: Testing the Configuration #

To test your autofs setup, try accessing the directory under which the remote shares should be automatically mounted:

ls /misc/data

If everything is configured correctly, you should see the contents of the NFS share listed without having manually mounted it.

Detailed Code Examples #

Here are detailed examples of the configurations used in a typical autofs setup:

Master File Configuration (/etc/auto.master) #

/misc   /etc/auto.misc
/net    -hosts

The above configuration also includes an entry for /net which automagically mounts hosts as needed.

Map File Configuration (/etc/auto.misc) #

data -fstype=nfs,rw,soft,intr,rsize=8192,wsize=8192 server.example.com:/export/data

This configuration specifies options relevant to NFS.

Conclusion #

autofs is a powerful tool for system administrators, offering a flexible and efficient way to manage file system mounts in a dynamic environment. By understanding and utilizing autofs, you can greatly enhance your system’s manageability and performance, especially in network-heavy environments.

For RHCSA candidates, mastering autofs not only helps in the exam but also in real-world scenarios where system efficiency and resource optimization are critical.