Wat is RAM/memory hot-plugging?

RAM/memory hot-plugging is the ability to dynamically add (hot-add) or remove (hot-remove) RAM to a running operating system, such as a server or virtual machine, without having to shut it down or reboot. 

RAM/memory hot-plugging enables on-demand scaling of a server’s memory. Is your server’s RAM load temporarily spiking, for example due to high demand on a hosted application? You can add more resources without a restart to meet that demand. This helps prevent downtime during upgrades or peak load. 

Using RAM/memory hot-plugging

You can use RAM/memory hot-plugging on our VPS platform under a few conditions:

• The VPS must have been created, or restarted via the reset button in the control panel, on or after 17 October 2025.
• Live addition of RAM is only possible on Windows Server 2022 or newer, and on Linux distributions.
• Live removal of RAM is only possible on Linux distributions.

Enabling RAM/memory hot-plugging on Linux

Enable hot-plugging (one-off) before adding extra RAM

On Linux distributions such as Ubuntu and AlmaLinux you can easily enable RAM/memory hot-plugging with a single command:

echo online | sudo tee /sys/devices/system/memory/auto_online_blocks

Note: Run this command once before adding RAM to your VPS. After that, it isn’t needed again. Have you already added extra memory? Then continue with the section below. 

Apply hot-plugging manually after adding extra RAM

Have you added extra RAM before enabling RAM hot-plugging (see above)? Then follow these steps to bring the new memory online without requiring a reboot.

First things first: is any manual action needed? Run the command below. If you only see ‘online’, you don’t need to change anything.

grep -H . /sys/devices/system/memory/memory*/state

Do you see ‘offline’ listed? Then run the following command to bring the memory online:

for s in /sys/devices/system/memory/memory*/state; do
  if [ "$(cat "$s")" != "online" ]; then
    echo online | sudo tee "$s" >/dev/null
  fi
done