What is a bare metal hypervisor?

Joseph McKeown -

Bare Metal Servers offer the power of a dedicated server with the flexible networking capabilities and pay-as-you-use billing of cloud hosting. This combination makes bare metal a winning choice for businesses looking for serious computing power and more control over their outgoings. To make their operations even more efficient, some even choose to run multiple VMs on their server, maximising their use of its resources.

But how does virtualising a bare metal server work? And where do hypervisors come in? Read on to learn all about it.

What is a bare metal server?

Put simply, a bare metal server is a single physical server dedicated entirely to one user or "tenant". This one tenant has exclusive access to all its resources, including RAM, storage and CPU. Along with dedicated servers, they’re known for delivering seriously powerful performance for high-intensity tasks, such as:

  • Big data analytics
  • Real-time comms
  • Forex trading
  • Gaming – especially for low latency demands
  • Machine learning and AI

What is a hypervisor?

A hypervisor, also known as a virtual machine monitor (VMM) is software that creates and runs virtual machines (VMs) and allocates server resources to each. This allows multiple operating systems to share the hardware of a single physical server. A "layer" is created between the hardware and each VM, effectively separating them and allowing them to operate without interfering with one another.

Bare metal hypervisors explained

A bare metal hypervisor (also known as a "Type 1" or "native" hypervisor) runs directly on the host's hardware, as opposed to within an operating system. This is in contrast to hosted hypervisors, which run within an OS. 

With a bare metal hypervisor, the hypervisor essentially replaces the host operating system. The hypervisor takes control of the physical server resources and partitions them into VMs that can run guest operating systems and applications.

So what’s the difference? A bare metal hypervisor and a hosted hypervisor differ in that the bare metal hypervisor interfaces directly with the underlying hardware – meaning there’s no operating system managing resources between the hypervisor and hardware.

In fact, we have a guide on creating a bare metal server with virtualisation, using Hyper-V, VMWare or VirtualBox. You’ll need some technical know-how to do this, but we can always assist if needed. You’ll also need to launch your CloudNX control panel to begin.

Hosted vs bare metal hypervisors

Hosted hypervisors run within the OS of the host’s machine, whereas bare metal hypervisors run directly on the computing hardware. So the key difference between hosted and bare metal hypervisors is where they run. 

Hosted hypervisors can run on Linux or Windows, but because bare metal hypervisors run directly on a server’s hardware, it removes the middleman (the OS) and makes room for better performance and efficiency due to the lack of OS overhead.

Some other key differences with bare metal hypervisors include:

  • Direct hardware access
  • Increased compatibility with other hardware
  • Increased isolation between virtual machines

What are the benefits of bare metal hypervisors?

Let’s dive into the advantages of bare metal hypervisors in greater detail.

1. Enhanced performance

Bare metal hypervisors don't have to share resources with any other operating systems because all of the server's resources are dedicated to running the VMs instead. This removes the "noisy neighbour" effect seen with most hosted hypervisors. Plus, with no operating system overhead, computing components are used efficiently across VMs.

2. Security

Hackers can’t target the OS of a bare metal hypervisor, because it doesn’t exist! With no intermediary, the hypervisor is further isolated between VMs. This doesn’t render a bare metal hypervisor completely invulnerable, but it’s one of the biggest selling points when it comes to data security.

3. Increased reliability

Again – the lack of OS helps with a bare metal hypervisor’s use case. If an OS crashes or fails, so does the hypervisor – which is not what you want in critical business conditions and workloads. This means high uptime for server usage too.

4. Efficient hardware use

Bare metal hypervisors give VMs direct access to the underlying physical hardware’s CPU, memory, storage, network and other components. But hosted hypervisors like VMware use some of these physical resources, meaning the hypervisor has to schedule and manage VM access to hardware, which adds CPU and memory overhead – reducing the total capacity available to the virtual machines.

Disadvantages of bare metal hypervisors

Here are some disadvantages of bare metal hypervisors to be aware of.

1. Set-up can be complex

Bare metal hypervisors require direct access to server hardware, so the initial setup is typically more complex than hosted virtualisation. Your IT team will need to have an understanding of the underlying hardware, not to mention not all hardware is compatible with every hypervisor out there. Besides this, there are other factors like load balancing and resource allocation to consider.

2. Costs

Management and maintenance of server hardware all factor into the costs associated with a bare metal hypervisor (either by a dedicated IT team or the server provider). There are also the complex installation processes that require dedicated and knowledgeable resources, which all factor in too. Although the associated costs are outweighed by their benefits, they may not be as accessible for smaller businesses.

3. Hardware dependence

Bare metal hypervisors depend entirely on the server’s hardware. If the physical server fails, all VMs will go down unless a failover cluster is pre-configured. Hosted VMs can be migrated to new hardware easily if issues emerge.

4. Vendor lock-in

Though this isn’t always the case, there may be a risk of vendor lock-in. As bare metal hypervisors run directly on the hardware, they may require specific driver and firmware support. With this in mind, it’s important to weigh up the options out there with different providers to ensure you’re getting the best value and performance possible.

Ready to get started with your own bare metal hypervisor? Contact us to find out more about how you can get the best out of our Bare Metal servers.