Qemu vs libvirt: What are the differences?

Key Differences between QEMU and libvirt

Introduction

QEMU and libvirt are both open-source software tools used in virtualization. While they are related and often used together, they serve different purposes and have distinct features.

1. Execution Environment: QEMU is primarily an emulator that provides full system emulation, allowing hardware virtualization and the ability to run various guest operating systems on different host platforms. On the other hand, libvirt is a library that provides a unified, high-level, and declarative API for managing virtualization technologies, including QEMU, KVM, Xen, and more.

2. Hardware Emulation: QEMU includes its own built-in CPU emulation, which allows it to run guest operating systems, even if they have different architectures than the host platform. In contrast, libvirt relies on the underlying capabilities of the hypervisor and does not provide direct hardware emulation.

3. Management Capabilities: QEMU provides a command-line interface for managing virtual machines and their associated resources. It allows users to start, stop, pause, and monitor virtual machines directly through commands. On the other hand, libvirt provides a high-level API and management toolset that abstracts the underlying virtualization technologies. It enables users to manage virtual machines through a consistent interface across different hypervisors.

4. Scalability: QEMU is well-suited for running a small number of virtual machines on a single host. It is often used for development and testing purposes. In contrast, libvirt provides a scalable management framework that can be used to manage multiple hosts and coordinate the deployment and migration of virtual machines across a cluster or network.

5. Integration with Virtualization Technologies: QEMU is a low-level component that can be used as a standalone tool or integrated with other virtualization technologies. It provides low-level access to the hardware and allows customization and fine-grained control. In contrast, libvirt is designed to abstract the underlying virtualization technologies and provide a common management interface. It offers a higher-level of abstraction and simplifies the management of virtual machines.

6. Community Support: QEMU has a large and active community of developers and users. It is widely used in the open-source community and has a rich ecosystem of tools, plugins, and extensions. Similarly, libvirt also has a strong community and is supported by leading virtualization vendors. It benefits from the collaborative efforts of various contributors and provides a well-documented and mature management framework.

In summary, QEMU is primarily an emulator that provides full system emulation and hardware virtualization capabilities, while libvirt is a management framework that abstracts the underlying virtualization technologies and provides a unified management interface across different hypervisors.