> For the complete documentation index, see [llms.txt](https://docs.platform9.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.platform9.com/private-cloud-director/2025.8/virtualized-clusters/virtualmachine/cpu-memory-hot-add-support.md).

# VM Hot-Add CPU Or Memory

<code class="expression">space.vars.product\_name</code> supports hot-add of CPU and / or memory resources to a running virtual machine. Using this feature, you can increase CPU cores or memory allocated to a running VM, without having to power-cycle it. This is valuable for production VMs that need more resources to meet workload demands but that can not be powered off.

## Pre-requisites

* Read more here about [Zero-Size Flavor](https://github.com/platform9/pcd-docs-gitbook/blob/main/private-cloud-director/2025.8/deploying-workloads/flavorless-vms-with-hot-plug.md#create-a-zero-size-flavor). Using **zero-size flavor** when creating your VM is a requirement for hot-add. Before you can hot-add CPU or memory resources to a VM, the VM must have been created using zero-size flavor.

## Hot-add CPU or Memory to a Running VM

1. Select a powered-on VM that was created with a zero-size flavor.
2. On the VM grid view, navigate to **▷** **Other** **Actions ▷ Hotplug**.
3. Enter the new vCPU and/or memory value for the VM. These values must not exceed the maximums set at the time of VM creation.
4. Click Hotplug VM.

## Limitations

* You can not use the hot-add feature to resize the disk of a running VM today.


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