How to Configure a tmpfs RAM Disk on Linux

Step-by-step guide to create, mount, and benchmark a tmpfs RAM disk on Linux, including persistent configuration using /etc/fstab

How to Configure a tmpfs RAM Disk on Linux

This guide explains how to create and configure a RAM-based filesystem using tmpfs on Linux systems, including mounting, persistence, and performance testing.

Prerequisites

  • Root or sudo access
  • Available system memory
  • Basic familiarity with Linux command line

1. (Optional) Install Monitoring Tools

Install htop to monitor memory usage:

dnf install htop -y

2. Create a Mount Point

Create a directory for the RAM disk:

sudo mkdir /mnt/ramdisk

Set permissions (optional, depending on use case):

sudo chmod 777 /mnt/ramdisk

3. Mount the RAM Disk

Mount a tmpfs filesystem with a defined size:

sudo mount -t tmpfs -o size=4G ramdisk /mnt/ramdisk

This creates a temporary RAM-backed filesystem limited to 4GB.

4. Configure Auto-Mount at Boot

Edit /etc/fstab

sudo nano /etc/fstab

Add Entry

tmpfs /mnt/ramdisk tmpfs nodev,nosuid,noexec,nodiratime,size=4096M 0 0

Alternative example:

plextmp /tmp/ramdisk tmpfs defaults,size=12G,x-gvfs-show 0 0

Key options:

  • size – Maximum RAM usage
  • nodev – Disable device files
  • nosuid – Ignore SUID bits
  • noexec – Prevent execution of binaries

5. Apply Mount Without Reboot

systemctl daemon-reload
sudo mount -a

This applies the fstab configuration immediately.

6. Test RAM Disk Performance

Write Test

sudo dd if=/dev/zero of=/mnt/ramdisk/testfile bs=4k count=1000000
sudo dd if=/dev/zero of=/tmp/testfile bs=4k count=1000000

Read Test

sudo dd if=/mnt/ramdisk/testfile of=/dev/null bs=4k count=1000000
sudo dd if=/tmp/testfile of=/dev/null bs=4k count=1000000

These tests compare RAM disk performance with standard disk storage.

7. Clean Up Test Files

rm -f /mnt/ramdisk/testfile
rm -f /tmp/testfile

Best Practices

  • Do not allocate more RAM than the system can safely provide
  • Use RAM disks for temporary or high-speed workloads only
  • Remember that data in tmpfs is lost on reboot
  • Monitor memory usage to prevent system instability

Use Cases

  • Temporary file storage
  • High-speed caching
  • Build environments
  • Application scratch space

Summary

A tmpfs RAM disk provides extremely fast storage by using system memory. It is ideal for temporary workloads and performance-sensitive applications, but should be used carefully due to its volatile nature.

Note: Data stored in tmpfs is not persistent and will be lost after reboot or unmount.

Last Updated: 
2026/02/10

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