# 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 <a href="#pre-requisites" id="pre-requisites"></a>

* Read more here about [Zero-Size Flavor](https://docs.platform9.com/private-cloud-director/virtualized-clusters/flavorless-vms-with-hot-plug#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 <a href="#hot-add-cpu-or-memory-to-a-running-vm" id="hot-add-cpu-or-memory-to-a-running-vm"></a>

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. The maximum allowable values are automatically set based on the VM configuration.
4. Click Hotplug VM.

### Limitations <a href="#limitations" id="limitations"></a>

* Hot add can only be used to increase the current CPU or memory allocation of a running VM. Reducing currently allocated CPU or memory is supported only while the VM is stopped.
* You can not use the hot-add feature to resize the disk of a running VM today.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.platform9.com/private-cloud-director/virtualized-clusters/virtualmachine/vm-hot-add-cpu-or-memory.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.