Managing swap: creation and resizing¶

Swap is a virtual memory mechanism that temporarily offloads inactive portions of RAM to secondary storage (disk), freeing up RAM for active processes.

Checking current swap status¶

Before making any changes, verify which swap is in use on the system:

swapon -s

Possible output variants:

1. No swap¶

If the output is empty or contains only the header:

Filename    Type    Size    Used    Priority

— swap is not configured in the system.

2. Swap partition in use¶

Example:

Filename        Type      Size     Used   Priority
/dev/vda5       partition 1046524  4568   -1

Here swap is implemented via a separate disk partition /dev/vda5. To increase the total swap volume, you can add a swap file—it will operate alongside this partition.

3. Swap file in use¶

Example:

Filename    Type    Size     Used   Priority
/swap       file    1048572  0      -1

Swap is organized through the file /swap. You can safely replace it with a larger file; the /etc/fstab entry is likely already present (step 6 of the instructions can be skipped).

Creating or resizing a swap file¶

1. Disable the current swap¶

sudo swapoff -a

2. Create (or recreate) a swap file of the desired size¶

Example for a 1 GB (1024 MiB) file:

sudo dd if=/dev/zero of=/swap bs=1M count=1024

Replace count=1024 with the desired size in megabytes (e.g., 512, 2048, 4096, etc.).

3. Set permissions and initialize swap¶

sudo chmod 600 /swap
sudo mkswap /swap

4. Enable swap¶

sudo swapon /swap

5. Verify the result¶

swapon -s

Expected output:

Filename    Type    Size     Used   Priority
/swap       file    1048572  0      -1

6. Make the changes permanent¶

To have swap automatically mount after reboot, add an entry to /etc/fstab:

echo "/swap none swap sw 0 0" | sudo tee -a /etc/fstab