Part II Managing virtual machines with libvirt #

A libvirt deployment for accessing KVM or Xen requires one or more daemons to be installed and active on the host. libvirt provides two daemon deployment options: monolithic or modular daemons. libvirt has always provided the single monolithic daemon libvirtd. It includes the primary hypervisor driv…

Before you can install guest virtual machines, you need to prepare the VM Host Server to provide the guests with the resources that they need for their operation. Specifically, you need to configure:

A VM Guest consists of an image containing an operating system and data files and a configuration file describing the VM Guest's virtual hardware resources. VM Guests are hosted on and controlled by the VM Host Server. This section provides generalized instructions for installing a VM Guest. For a l…

Most management tasks, such as starting or stopping a VM Guest, can either be done using the graphical application Virtual Machine Manager or on the command line using virsh. Connecting to the graphical console via VNC is only possible from a graphical user interface.

Managing several VM Host Servers, each hosting multiple VM Guests, quickly becomes difficult. One benefit of libvirt is the ability to connect to several VM Host Servers at once, providing a single interface to manage all VM Guests and to connect to their graphical console.

This chapter introduces advanced topics about manipulating storage from the perspective of the VM Host Server.

Virtual Machine Manager's Details view offers in-depth information about the VM Guest's complete configuration and hardware equipment. Using this view, you can also change the guest configuration or add and modify virtual hardware. To access this view, open the guest's console in Virtual Machine Manager and either choose View › Details from the menu, or click Show virtual hardware details in the toolbar.

You can use virsh to configure virtual machines (VM) on the command line as an alternative to using the Virtual Machine Manager. With virsh, you can control the state of a VM, edit the configuration of a VM or even migrate a VM to another host. The following sections describe how to manage VMs by using virsh.

One of the major advantages of virtualization is that VM Guests are portable. When a VM Host Server needs maintenance, or when the host becomes overloaded, the guests can be moved to another VM Host Server. KVM and Xen even support “live” migrations during which the VM Guest is constantly available.

As the KVM virtualization solution is becoming more and more popular among server administrators, many of them need a path to migrate their existing Xen based environments to KVM. As of now, there are no mature tools to automatically convert Xen VMs to KVM. There is, however, a technical solution th…