In 2023, Broadcom acquired VMware and immediately announced the end of perpetual licences, termination of the free version of ESXi, and the switch to a subscription model. This decision has meant many companies around the world have experienced costs rising by 100-300%, prompting them to look for new alternatives.

Davidson has chosen to launch a pilot with the KVM solution, an open-source virtualisation solution, for our OKD (Openshift) containerisation platform.

Choosing an open-source platform has many benefits, including no licensing fees, autonomy in relation to proprietary vendors and freedom of use

What is OKD?

In the containerisation world, OKD (OpenShift) is a container orchestration platform designed to accelerate application development, deployment, and scaling. It enables developers and operational teams to effectively manage applications’ lifecycles over the long term.

What’s the difference between OKD and OpenShift?

According to Red Hat documentation, OKD is the basis for OpenShift. Initially known as OpenShift Origin, OKD is now recognised as “a community project comprising software components that run above Kubernetes”. In other words, OKD is the community version of OpenShift.

OKD in Davidson’s IT department

The YODA team manages around fifty internal applications for Davidson. Most of these applications are hosted on the OKD platform. It is used to simplify the development, deployment, and management of these container-based applications.

POC objective

Currently, at YODA, we use OKD in conjunction with VMware vSphere, a virtualisation solution, to deploy, run and manage the lifecycle of our applications. VMware is a leader in virtualisation, offering the ESXi hypervisor and the vSphere platform. However, these solutions require paid licences. The objective of our Proof of Concept (POC) is to find and assess an optimised virtualisation alternative for OKD. This alternative must offer a lower total cost of ownership while being as powerful, high-performing, simple, stable, and secure as VMware.

Comparison between KVM and VMware for virtualisation

• Architecture

KVM works as a module of the Linux kernel, meaning it is tightly integrated with the host operating system. KVM virtual machines are managed as normal Linux processes, allowing compatibility with all standard Linux tools and easy management via system commands.

VMware ESXi, on the other hand, is a type 1 hypervisor that runs directly on the hardware, without an intermediary. This minimises the load on the host system and provides strong isolation between virtual machines, thereby reducing the risk of conflicts.

• Performance

KVM has excellent performance thanks to its proximity to the Linux kernel and efficient use of hardware virtualisation extensions. However, the need for a host operating system can introduce a slight overload.

VMware, with ESXi, typically offers superior performance because it runs directly on the hardware. This architecture minimises latency and maximises efficiency, which is crucial for environments that require peak performance.

• Management and administration

KVM uses tools like libvirt, virt-manager, and other CLI interfaces to manage virtual machines. These tools, although powerful, may require a learning curve and be less user-friendly than modern graphical interfaces.

VMware provides sophisticated, well-designed management solutions, such as vCenter, that make it easy to centrally manage large-scale virtualisation environments. These tools offer advanced functionality for automation, monitoring and orchestration.

• Scalability and resilience

KVM can scale efficiently to meet growing needs with features such as live VM migration. However, additional effort may be needed for advanced configuration for very large environments.

VMware is known for its ability to easily scale and manage complex environments. Features such as high availability (HA), fault tolerance and clustering are built-in, making it an ideal choice for critical scenarios where resilience is essential.

• Security

KVM benefits from Linux inherent security, with features like SELinux and AppArmor adding additional layers of protection. However, security depends largely on the configuration and management of the host environment.

VMware offers robust, integrated security solutions, such as VMware NSX for network security virtualisation. VMware environments are often certified to meet high security standards, which is an asset for organisations that require enhanced security.

• Cost

As KVM is open source, it is generally less expensive than commercial solutions. There is no licensing fee for using KVM, making it an attractive option for low-budget organisations. The associated costs are mainly related to support and management.

Although VMware is more expensive, it offers a range of features and services that often warrant the investment. Costs include licences for the ESXi hypervisor, vCenter for centralised management, and other add-on modules. For large companies, these costs can be offset by the benefits in terms of performance, management and resilience.

• Ecosystem and support

KVM, as an open source solution, has a vast ecosystem and a dynamic community. Several Linux distributions integrate it, and many resources and forums are available for support. However, in order to benefit from sales support, purchasing third-party services may be required.

VMware offers a mature ecosystem with a wide range of complementary products and partners. VMware’s commercial support is renowned for its quality with extensive support options available to enterprises. The VMware ecosystem is also well integrated with partner solutions for extended functionality.

So why choose KVM?

KVM (Kernel-based Virtual Machine) is an open source virtualisation technology that converts the Linux kernel into a powerful hypervisor. It effectively virtualises enterprise workloads and provides all the functionality needed to manage both physical and virtual infrastructures, all at a lower operating cost.

The KVM solution strong points:

• Cost:
  • Cost-effective: as an open source technology, KVM does not incur any additional licensing costs. This significantly reduces the total cost of ownership (TCO) compared to proprietary virtualisation solutions.
• Open Source:
  • Innovation and Flexibility: access to the KVM source code allows developers to innovate and tailor the solution to their specific needs. This fosters great flexibility in managing and developing virtual environments.
  • Independence: by using KVM, companies avoid relying on a single vendor, giving them freedom in choosing and managing their infrastructure.
• Performance:
  • High Performance: KVM delivers performance close to native hardware, without overloading a hypervisor layer. This means that applications run faster and more efficiently than other hypervisors.
  • Interoperability: KVM provides excellent compatibility between Linux and Windows platforms, allowing seamless management of heterogeneous systems.
• Compatibility and integration:
  • Linux kernel integration: thanks to its direct integration into the Linux kernel, KVM is widely adopted in Linux-based environments. It takes advantage of Linux’s strengths, including security, memory management, process scheduling, network and peripheral device drivers.
  • Integration with OKD: its compatibility with Red Hat distributions and close integration with Kubernetes-based solutions, such as OKD, make it an attractive option for container deployments.
• Easy to use:
  • Centralised management: KVM makes it easy and efficient to create, start, stop, pause, migrate and model hundreds of virtual machines. KVM offers centralised and simplified management of virtual environments, whether on varied hardware or software.

Setting up an OKD cluster with KVM: the prerequisites

To install KVM, a host server with Fedora Core OS is required. This operating system provides the basis on which the KVM will be installed and configured.

One might wonder why an operating system is needed when KVM is described as a type 1 hypervisor, which is supposed to run directly on the hardware. In fact, KVM is a module embedded in the Linux kernel, which activates virtualisation. The operating system, such as Fedora Core OS in this case, serves as support for this module. Once KVM is enabled, it uses the hardware directly as a traditional hypervisor would.

To sum up:

• Host machine: the host machine runs under a Linux distribution, providing the environment necessary for KVM to be installed and used.
• KVM Hypervisor: once enabled in the operating system, KVM connects directly to the hardware and enables virtual machine management.