# Differences of bare metal and virtual machines

## Bare metal

Bare metal clusters provide direct access to physical hardware for greater control and customization of the environment.  This includes but is not limited to:

* physical CPUs, not virtualized CPUs
* no hypervisor overhead which requires host CPU and memory resources
* ability to change symmetric multi threading (SMT) and NUMA BIOS settings
* full access to local NMVe block devices to configure filesystems and RAID
* enhanced security by removing the hypervisor layer

Denvr Cloud has limited observability into bare metal hosts which which requires additional responsibility of the tenant to monitor and report system issues for analysis.

## Virtual machines

Virtual machines provide access to GPUs and compute resources with a minor overhead required for the hypervisor.  The primary benefits of virtualization, even for full nodes, are:

* choice of operating system images to use during provisioning
* 1-5 minutes to boot the instance (depends primarily on number of vCPUs assigned)
* ability to resize allocated resources (CPU, memory disks) as requirements change
* less likelihood of over-provisioning resources versus large bare metal hosts
* usage of snapshots for backups and starting new instances
* self-service management via Denvr Cloud console and APIs

{% hint style="success" %}
GPU processing and InfiniBand/RoCE fabrics are not impacted by virtualization as the devices are passed-through to the guest O/S.  This provides the same level of performance, control, and isolation benefits as a bare metal host.
{% endhint %}

## Feature comparison

### Performance

<table><thead><tr><th width="203"> </th><th width="251">Bare Metal</th><th>Virtual Machines</th></tr></thead><tbody><tr><td>Overhead</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> None</td><td>Hypervisor requires CPU and memory resources</td></tr><tr><td>Consistency</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> High consistency in performance</td><td>Potential variability in performance</td></tr></tbody></table>

### Security

<table><thead><tr><th width="204"> </th><th>Bare Metal</th><th>Virtual Machines</th></tr></thead><tbody><tr><td>Tenant isolation</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2714">✔️</span> Single tenant only</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2714">✔️</span> Single or multi-tenant</td></tr><tr><td>Multi-user access</td><td>May require additional software to manage user isolation and Quality of Service</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> Quality of service is enforced</td></tr><tr><td>Security risk</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> Lowest risk of cross-tenant impact</td><td>Higher risk due to shared infrastructure.  Virtualization is a mature technology in use since the early 2000's.</td></tr><tr><td>Data privacy</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2714">✔️</span> Denvr has no mechanism to access the system, including for operational support</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2714">✔️</span> Denvr can monitor and maintain the system hardware instead of the user </td></tr></tbody></table>

### Management

<table><thead><tr><th width="204"> </th><th>Bare Metal</th><th>Virtual Machines</th></tr></thead><tbody><tr><td>Node types</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2714">✔️</span> Full node only</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2714">✔️</span> Allows customization of machine resources including single-GPU instances</td></tr><tr><td>Scalability</td><td>Full node only</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> Instance sizes can be changed dynamically without re-provisioning</td></tr><tr><td>Software and drivers</td><td>Denvr only installs the GPU and fabric drivers.</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> Pre-configured images are available with required software dependencies.</td></tr><tr><td>Time to launch</td><td>Slower</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> Fastest</td></tr><tr><td>Backup and restore</td><td>Difficult to backup the operating system for recovery</td><td><span data-gb-custom-inline data-tag="emoji" data-code="2705">✅</span> Simple to snapshot, clone, copy, and duplicate machine images.</td></tr></tbody></table>


---

# 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.denvrdata.com/docs/additional-information/faqs/differences-of-bare-metal-and-virtual-machines.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.