KVM vs XenServer: What are the differences?

Introduction

Here, we will explore the key differences between KVM and XenServer, two popular virtualization technologies.

1. Hypervisor Type: KVM (Kernel-based Virtual Machine) is a full virtualization solution, whereas XenServer is a hybrid hypervisor that supports both paravirtualization and full virtualization. KVM virtualizes the hardware resources directly using the host's kernel, while XenServer uses a hypervisor layer between the host operating system and the virtual machines.

2. Platform Support: KVM is primarily a Linux-based virtualization solution and works best on Linux platforms. On the other hand, XenServer is a hypervisor that can run on multiple operating systems, including Linux, Windows, and FreeBSD. It provides broader platform support compared to KVM.

3. Management Tools: KVM relies on open-source management tools like libvirt and virt-manager for managing virtual machines. XenServer, on the other hand, offers a proprietary management tool called XenCenter. XenCenter provides a user-friendly GUI and advanced management features like live migration and high availability, making it more suitable for enterprise environments.

4. Performance: KVM leverages hardware virtualization extensions (Intel VT and AMD-V) to provide near-native performance. This allows KVM to achieve better performance compared to XenServer, especially for workloads that require high CPU utilization. However, XenServer's paravirtualization approach can offer better overall performance in certain scenarios, especially when running multiple virtual machines on a single host.

5. Virtualization Overhead: KVM has a relatively low virtualization overhead since it runs virtual machines directly on the host operating system. On the other hand, XenServer introduces an additional layer (the hypervisor) between the host and the virtual machines, which can potentially impact performance to some extent. However, the actual overhead may vary depending on factors like workload type and system configuration.

6. Licensing: KVM is an open-source virtualization solution and is included in the Linux kernel. It is available for free and has no licensing costs. XenServer, on the other hand, has a commercial license model. While it offers a free version called XenServer Free, certain advanced features and support require a paid license.

In summary, KVM is a full virtualization solution primarily focused on Linux platforms, while XenServer is a hybrid hypervisor with broader platform support. KVM provides better performance and has lower virtualization overhead, while XenServer offers advanced management tools, paravirtualization capability, and a commercial licensing model.