How to Increase Swap Size on Ubuntu Linux

Running out of memory on your Ubuntu system? If your applications are sluggish or crashing under heavy load, it might be time to increase your swap space. Swap is the portion of disk used as virtual memory when RAM is full. It’s not a performance booster, but it can prevent crashes and keep things running when RAM is maxed out.

Here’s a no-nonsense guide to increasing swap size on Ubuntu.

Check Your Current Swap Setup

First, see how much swap you’re using:

swapon --show

If that returns nothing, you probably don’t have swap configured. You can confirm with:

free -h

Step 1: Turn Off Existing Swap (If Needed)

If you’re increasing an existing swap file:

sudo swapoff /swapfile

Step 2: Resize or Create a New Swap File

Option A: Resize Existing Swap File

Let’s say you want to increase it to 4GB:

sudo dd if=/dev/zero of=/swapfile bs=1G count=4

Or if you already have a swap file and just want to resize it:

sudo truncate -s 4G /swapfile

Option B: Create a New Swap File (if none exists)

sudo fallocate -l 4G /swapfile

Step 3: Set Correct Permissions

sudo chmod 600 /swapfile

Step 4: Format the Swap File

sudo mkswap /swapfile

Step 5: Enable the Swap File

sudo swapon /swapfile

To confirm:

swapon --show

Step 6: Make It Permanent

Edit the /etc/fstab file:

sudo nano /etc/fstab

Add this line if it’s not already there:

/swapfile none swap sw 0 0

Save and exit.

Bonus: Adjust Swappiness (Optional)

Swappiness controls how aggressively Ubuntu uses swap. Default is 60. If you want it to favor RAM more, lower it:

sudo sysctl vm.swappiness=10

To make it permanent:

echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf

Done

That’s it. You’ve increased your swap space. This can be a lifesaver for servers, older machines, or systems doing heavy multitasking.

Have questions or want help tweaking your system? Drop them in the comments below.