RHEL7: How to configure /tmp on tmpfs.

Presentation

Some applications writing files in the /tmp directory can see huge improvements when memory is used instead of disk.

By default in RHEL 7 / CentOS 7, the /tmp directory resides in the logical volume/physical partition associated with /:

# df -k /tmp
Filesystem            1K-blocks    Used Available Use% Mounted on
/dev/mapper/rhel-root   3030800 1069380   1787752  38% /

Here, another way to check the configuration:

# systemctl is-enabled tmp.mount
disabled

Configuration Change

To change this behavior and put the /tmp directory on tmpfs, type:

# systemctl enable tmp.mount

Now, if you check the new configuration, this is what you get:

# df -k /tmp
Filesystem     1K-blocks  Used Available Use% Mounted on
tmpfs             508988     8    508980   1% /tmp

Remember not to write big files due to the limited space and, obviously, don’t expect persistence across reboots.

Additional Resources

In the same spirit, you can read this interesting article about Managing Temporary Files.
You can also have a look at this article about Tmpfs and Bind Mounts.