Many organizations over-provision when it comes to server hardware, leading to extra costs for colocation and maintenance. Server virtualization can help reduce these costs and make better use of that hardware. But what is server virtualization? It's the practice of using software to divide a single physical server into several virtual machines (VMs), each of which can run a different operating system. These virtual servers can be used for various purposes, like running web or database servers, or remote desktop operating systems. One of the main benefits of server virtualization is that it helps IT teams make the most out of their hardware, ensuring their powerful servers are not underutilized.
How Does Server Virtualization Work?
Server virtualization uses a hypervisor to let a host server run several guest VMs. Each VM acts like a full computer with shared access to the host's processing power, storage and other resources. This means that the hypervisor can either run directly on the host hardware or within the host's operating system. Each guest runs within the hypervisor. To the guest operating system, the VM will appear to be a physical computer with whatever system resources the hypervisor makes available.
If your organization uses dedicated servers for each workload, it's likely that those servers are sitting at around 20% utilization most of the time. Virtualization helps you get more out of each dedicated server.
The Three Types of Server Virtualization
There are three key varieties of server virtualization: Full-, para- and OS-level virtualization. Each of these options uses a hypervisor but in slightly different ways. Check out our hypervisor glossary page to learn more about hypervisors and how they work.
Full virtualization uses hypervisors to divide the host computer into multiple VMs with predefined resources. The hypervisor then communicates with the server to monitor and manage resource usage. A key feature of full virtualization is that the guest machines don't need to be aware of each other's existence in order to work.
Para-virtualization is similar to full virtualization, except that the VMs are aware of each other on the hypervisor. This allows VMs to work together to share resources.
OS-level virtualization is the most basic type of virtualization. Rather than relying on a hypervisor, the VMs are managed by the host's operating system instead. This solution is generally easier to implement and maintain, but it has the drawback of requiring each guest to run the same operating system.
Why Server Virtualization?
Server virtualization can greatly reduce IT overhead and improve scalability by allowing organizations to deploy virtual servers at will. There are several potential benefits of server virtualization, including:
Consolidation of physical servers: Rather than having several underutilized physical servers that still require monitoring and maintenance, smaller jobs can now be consolidated into one or more host servers that run several VMs each. This reduces colocation costs.
The option for redundancy: It's now possible to have backup copies of virtual servers on more than one machine. In the event of a hardware or network outage, users can launch important VMs on different hosts.
Scalability and flexibility: IT teams can create, run and shut down virtual servers as needed, without the expense and time delays that come with setting up physical hardware.
Security: VMs can be useful for testing services or applications in a sandboxed environment.
Ease of migration: Relocating a physical server requires a significant time investment. However, relocating a VM just requires copying that VM to a host server in the new location, reducing the downtime associated with migrations.
Common Use Cases for Server Virtualization
Server virtualization is a good option for enterprise organizations that require both scalability and flexibility. It offers:
Maximum use of available hardware: Users can consolidate several less resource-hungry servers into more powerful hardware.
Flexibility for development and testing environments: Developers can create VMs for testing environments, each with a predefined configuration that makes it easier for developers to collaborate.
Support for multiple operating systems: Server virtualization makes it possible to run Linux, BSD, Windows and other operating systems on the same hardware.
The ability to support legacy software: Organizations that rely on legacy software (like DOS or older Windows applications) may be able to run those workloads in VMs on modern hardware more efficiently than they would by just keeping outdated hardware running.
Alternatives to Server Virtualization
Server virtualization is a useful tool, but it’s not applicable to every use case. Some computing tasks don't require a full VM and the associated overhead that comes with running an additional copy of the operating system. For those cases, container solutions like Docker may be a better choice.
Containers use operating system virtualization to run isolated versions of an application or microservice. They hold the application's code, dependencies and any runtime libraries that are required by the application. Containers are more limited than VMs in that they rely on the same base operating system as the host. However, they offer security benefits compared to simply running the application directly on the host OS while still being a more lightweight option than a full VM.
Choosing the Right Server Virtualization Software
There are several issues to consider when choosing server virtualization software, including:
Potential cost savings: Consider the cost of virtualization software licenses and any maintenance burden versus the cost savings that come from increasing your hardware usage.
Ease of management: How easily can you deploy, manage and monitor the VMs running on your host?
Hardware compatibility: Hosted hypervisors are generally compatible with most modern hardware, but bare metal hypervisors may have more limited support. However, if the hardware you plan to use is compatible with them, there could be performance benefits.
Support and maturity: Virtualization is a significant investment, and switching software providers can be a time-consuming and costly task. Make sure you feel confident in the provider you choose, both in terms of their support provisions and security and their compatibility updates in the long term.
Ongoing costs: The cost of virtualization is not limited to the cost of buying the platform. It's important to consider the licensing costs behind the number of VMs and the software that runs on them, as well as any work done by in-house IT teams to keep the platform up to date.
How to Get Started
If you're considering getting started with server virtualization, start by auditing your existing hardware and your level of resource utilization. If you determine that you have underutilized servers and could benefit from consolidation, you'll need to choose a virtualization solution. Some popular options include:
After selecting your hypervisor, consider whether you'll need other tools to make it easier to manage your VMs. For example, Proxmox and Kimchi are often used with KVM.
In addition, consider how you'll create your VMs. One option is to use tools like Disk2VHD to clone an existing server and convert the drive image into popular virtual hard disk formats. These tools can save you a lot of time compared to manually performing the setup on a VM.
Once you've set up your VMs, test them to ensure they perform well and have full network connectivity. If you encounter any issues, tweak the settings and test again. Finally, set up a regular backup schedule and choose the right backup tools for your platform, so you'll have a current working copy of the VM ready to redeploy in the event of an outage.