Alternatives to Xen: 5 options under consideration

Overview of the best alternatives to Xen

KVM

KVM (Kernel-based Virtual Machine) is Linux-based virtualization software that has been part of the Linux kernel since version 2.6.20. Red Hat's software can certainly be used as a type 1 hypervisor via a custom installation like Xen. However, operation as an abstract application (type 2) is intended by default, which is why KVM is often classified as hybrid hypervisor solution. Possible guest systems you can run with this Xen alternative are, among others, BSD (Berkeley Software Distribution), Solaris, Windows, ReactOS and macOS.

Direct integration into the Linux kernel allows KVM to regularly receive security and performance updates. Generally speaking, the hypervisor stands out with an excellent security package: a combination of SELinux and sVirt (secure virtualization) ensures the security and isolation of your virtual machines. By implementing KVM on one of the supported Linux distributions, such as RHEL, you can expand the palette of functions. This allows you to improve system performance or exchange resources between guest systems.

VirtualBox

VirtualBox is another alternative to Xen, managed since 2008 by the American company Oracle. Originally, this virtualization software was developed by the company InnoTek Systemberatung GmbH, in Germany. Unlike Xen, VirtualBox is a hypervisor type 2 which works on Windows, Linux, macOS and Solaris platforms. As for guest systems, the application has practically no restrictions: in addition to Windows and Linux systems, various editions of Solaris and BSD are also possible as hosts. VirtualBox thus offers greater flexibility and the possibility of virtualizing the deskwhich is not the case for Xen.

The migration of virtual machines (VM or virtual machines) created is less flexible: in VirtualBox it is not possible to move VMs between physical hosts without downtime during live operation. There migration requires a manual process, this is why the virtualization application is less suitable for projects that require very high availability. An obvious advantage of Oracle's software is its ease of use for beginners. User interface chart makes managing virtual machines child's play, even for the uninitiated who otherwise have little to do with command line input as in Xen.

Xvisor

Xvisor (eXtensible Versatile hypervISOR) is, like Xen, an open source type 1 hypervisor which is distinguished by its very high flexibility and portability. This is reflected in the large number of architectures supported by Xvisor: in addition to x86 and x86_64, ARM and RISC-V are among the supported CPU architectures. Xvisor source code can be ported to any 32- and 64-bit platform, as long as a Paged Memory Management Unit (PMMU) and a GNU C Compiler (GCC) port are available. This alternative to Xen mainly focuses on complete virtualization and therefore allows a large number of unmodified guest OSes. For the host system, however, we are linked to a Linux distribution.

Virtualization with Xvisor is efficient and saves disk space, which can also be explained by the fact that the software does not use any security extensions. Paravirtualization as in Xen can be activated as an option, as long as the architecture used allows it.

QEMU

QEMUshort for Quick EMUlator, is an alternative to Xen that can be used either as an emulator or a type 2 hypervisor. Used as a hypervisor, QEMU achieves close native performance by running guest code directly on the host CPU. However, the virtualization software must use either the Xen hypervisor or the Linux KVM kernel module for this purpose. Compared to Xen, however, QEMU offers a much broader ecosystem and supports a significantly larger number of architectures and operating systems. This makes the program suitable for many uses, including development, control and operation of existing software.

As a Type 2 hypervisor, QEMU does not have direct access to hardware resources, which is why it is not quite on par with Xen in terms of performance. On the other hand, the tool offers a much more user-friendly interface thanks to a graphical user interface. QEMU has a large and active community which ensures regular updates. This virtualization solution has also been integrated with many other virtualization solutions and Cloud platforms.

UTM

UTM is a virtualization solution for emulating various operating systems on your device Mac, iPhone or iPad (from iOS 11). The software notably uses Apple's hypervisor virtualization framework to run ARM64 operating systems on devices equipped with an Apple Silicon processor with near-native performance. On older Macs with an Intel processor, you virtualize guest systems with x86 and x86_64 architecture if necessary. Additionally, the hypervisor supports various other architectures such as ARM32, MIPS, PPC, and RISC-V. This alternative to Xen is therefore an excellent choice, for example, if you want to run Windows systems on your Mac or iOS mobile device.

The basis of UTM is the already presented QEMU solution. This is certainly very flexible and efficient, but like Xen, it is not easy to master for beginners: due to the multitude of command line options and flags, these two options are difficult to set up and to configure against UTM. The virtualization solution was therefore developed with the aim of offering users the flexibility of QEMU while also being friendly as possible.