KVM vs. VMware

A hypervisor provides the foundation for your virtualization platform, and there are many choices from traditional vendors to open source alternatives. VMware is a popular choice for virtualization, and offers the ESXi hypervisor and vSphere virtualization platform. Kernel-based Virtual Machine (KVM) is an open source option and is part of Linux^®.

VMware offers the ESXi hypervisor and vSphere virtualization platform. VMware ESXi is a bare-metal hypervisor that installs directly onto a physical server and helps you to consolidate your hardware. VMware’s virtualization technologies allow you to create and provision virtual machines (VMs) so you can modernize your infrastructure to deliver and manage new and legacy applications.

Choosing VMware vSphere means you will need to manage your VMs using VMware’s control stack, and there are several license entitlement levels available.

KVM is an open source virtualization technology that changes the Linux kernel into a hypervisor that can be used for virtualization and is an alternative to proprietary virtualization technologies, such as those offered by VMware.

Migrating to a KVM-based virtualization platform means being able to inspect, modify, and enhance the source code behind your hypervisor. Having access to the source code opens the door to innovation, allowing you to virtualize traditional workloads and applications, and also build a foundation for cloud-native and container-based workloads. And because KVM is built into the Linux kernel, it’s easy to use and deploy.

Performance

One of the most important areas to consider is how the hypervisor’s performance will impact your infrastructure. KVM and ESXi are both type 1 hypervisors, which means they should outperform a type 2 hypervisor.

ESXi generally requires more time to create and start a server than KVM. ESXi also has slower performance when running servers, although this difference may be insignificant for typical loads. In terms of speed, KVM runs applications at near-native speeds, faster than other industry hypervisors, according to the SPECvirt_sc2013 benchmark.

Integration

Hypervisors use different methods to communicate with the physical hardware of the host. ESXi uses VMware’s management platform, which means you will need to use other products in VMware’s control stack. This can also increase your hardware requirements.

You won’t have the same restrictions with KVM because it is open source and can be integrated with your existing infrastructure and with many different Linux and Windows platforms.

Cost

Cost is a key differentiator between KVM and the VMware virtualization solutions. KVM is distributed as part of many open source operating systems, so there isn’t an additional cost. With VMware, you will need to purchase licenses for various products and will be locked into an enterprise license agreement (ELA). Although an ELA may save you budget up front, it can increase your costs over time with incremental gains in capacity and functionality in return. Overall, KVM has a lower total cost of ownership.

Maturity

Both KVM and ESXi are mature and stable hypervisors that can support enterprise workloads.

Scalability

VMware offers a scalable virtualization platform, however it’s important to consider how adding additional hosts or VMs might impact an ELA. vSphere offers a maximum of 12TB of RAM per host with a maximum of 64 hosts per cluster. vSphere includes several application programming interfaces (APIs) that can be used to make management of your VMs easier.

As part of the Linux kernel, KVM scales to match the demand load if the number of guest machines and requests increases. With KVM, the most demanding application workloads can be virtualized, and it is the basis for many enterprise virtualization setups, such as data centers and private clouds.

KVM is also interoperable with your existing infrastructure and gives you access to the source code, which means it is easy to integrate and scale however you need.

Support

With VMware, you will get enterprise-level support as part of your ELA. With KVM, you will need to rely on support from the open source community and your own IT organization, or a supported vendor like Red Hat.

VMware offers a well-established, stable hypervisor with excellent performance and features. But proprietary virtualization can keep you from having the resources to invest in clouds, containers, and automation. By removing vendor lock-in, you give yourself the freedom, flexibility, and resources to build the foundation for a cloud-native and containerized future.

KVM is production-ready for enterprise workloads with the features you need to support your physical and virtual infrastructure, at a lower operating cost. Choosing a virtualization option based on KVM has many advantages over other solutions, like VMware vSphere.

KVM has:

• Lower total cost of ownership, freeing up operating budget to explore modern, innovative technologies.
• No vendor lock-in. Don’t pay for products you aren’t using or restrict your software choices.
• Cross-platform interoperability: KVM performs on Linux and Windows platforms so you get more out of your existing infrastructure investments.
• The simplicity of a single virtualization platform to create, start, stop, pause, migrate, and template hundreds of VMs on hundreds of other hardware or software.
• Excellent performance: Apps run faster on KVM compared with other hypervisors.
• The open source advantage: Access the source code and get the flexibility to integrate with anything.
• Existing features of the Linux operating system:
  • Security features
  • Memory management
  • Process scheduler
  • Device drivers
  • Network stack

Red Hat OpenShift® Virtualization is a feature of Red Hat OpenShift based on KVM and Kubevirt. With OpenShift Virtualization, you can migrate your traditional VMs into containerized workflows and deploy VMs side-by-side with containers–all on a single platform. This allows you to preserve your investments in virtualization while taking advantage of the simplicity and speed of a modern application platform. Existing virtual machines can be migrated from other platforms onto the OpenShift application platform through the use of free, intuitive migration tools.