7.2. Creating guests with virt-manager

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virt-manager, also known as Virtual Machine Manager, is a graphical tool for creating and managing guests.

Procedure 7.1. Creating a guest with virt-manager

  1. Open virt-manager

    Start virt-manager. Launch the Virtual Machine Manager application from the Applications menu and System Tools submenu. Alternatively, run the virt-manager command as root.
  2. Optional: Open a remote hypervisor

    Open the File -> Add Connection. The dialog box below appears. Select a hypervisor and click the Connect button:
  3. Create a new guest

    The virt-manager window allows you to create a new virtual machine. Click the New button to create a new guest. This opens the wizard shown in the screenshot.
  4. New guest wizard

    The Create a new virtual machine window provides a summary of the information you must provide in order to create a virtual machine:
    Review the information for your installation and click the Forward button.
  5. Name the virtual machine

    Provide a name for your guest. Punctuation and whitespace characters are not permitted in versions before Red Hat Enterprise Linux 5.5. Red Hat Enterprise Linux 5.5 adds support for '_', '.' and '-' characters.
    Press Forward to continue.
  6. Choose virtualization method

    The Choosing a virtualization method window appears. Choose between Para-virtualized or Fully virtualized.
    Full virtualization requires a system with Intel® VT or AMD-V processor. If the virtualization extensions are not present the fully virtualized radio button or the Enable kernel/hardware acceleration will not be selectable. The Para-virtualized option will be grayed out if kernel-xen is not the kernel running presently.
    If you connected to a KVM hypervisor, only full virtualization is available.
    Choose the virtualization type and click the Forward button.
  7. Select the installation method

    The Installation Method window asks for the type of installation you selected.
    Guests can be installed using one of the following methods:
    Local media installation
    This method uses a CD-ROM or DVD or an image of an installation CD-ROM or DVD (an .iso file).
    Network installation tree
    This method uses a mirrored Red Hat Enterprise Linux installation tree to install guests. The installation tree must be accessible using one of the following network protocols: HTTP, FTP or NFS.
    The network services and files can be hosted using network services on the host or another mirror.
    Network boot
    This method uses a Preboot eXecution Environment (PXE) server to install the guest. Setting up a PXE server is covered in the Red Hat Enterprise Linux Deployment Guide. Using this method requires a guest with a routable IP address or shared network device. See Chapter 10, Network Configuration for information on the required networking configuration for PXE installation.
    Set the OS type and OS variant.
    Choose the installation method and click Forward to proceed.


    Para-virtualized installation must be installed with a network installation tree. The installation tree must be accessible using one of the following network protocols: HTTP, FTP or NFS. The installation media URL must contain a Red Hat Enterprise Linux installation tree. This tree is hosted using NFS, FTP or HTTP.
  8. Installation media selection

    This window is dependent on what was selected in the previous step.
    1. ISO image or physical media installation

      If Local install media was selected in the previous step this screen is called Install Media.
      Select the location of an ISO image or select a DVD or CD-ROM from the dropdown list.
      Click the Forward button to proceed.
    2. Network install tree installation

      If Network install tree was selected in the previous step this screen is called Installation Source.
      Network installation requires the address of a mirror of a Linux installation tree using NFS, FTP or HTTP. Optionally, a kickstart file can be specified to automated the installation. Kernel parameters can also be specified if required.
      Click the Forward button to proceed.
    3. Network boot (PXE)

      PXE installation does not have an additional step.
  9. Storage setup

    The Storage window displays. Choose a disk partition, LUN or create a file-based image for the guest storage.
    All image files are stored in the /var/lib/libvirt/images/ directory by default. In the default configuration, other directory locations for file-based images are prohibited by SELinux. If you use a different directory you must label the new directory according to SELinux policy. See Section 19.2, “SELinux and virtualization” for details.
    Your guest storage image should be larger than the size of the installation, any additional packages and applications, and the size of the guests swap file. The installation process will choose the size of the guest's swap based on size of the RAM allocated to the guest.
    Allocate extra space if the guest needs additional space for applications or other data. For example, web servers require additional space for log files.
    Choose the appropriate size for the guest on your selected storage type and click the Forward button.


    It is recommend that you use the default directory for virtual machine images, /var/lib/libvirt/images/. If you are using a different location (such as /images/ in this example) make sure it is labeled according to SELinux policy before you continue with the installation. See Section 19.2, “SELinux and virtualization” for details.
  10. Network setup

    Select either Virtual network or Shared physical device.
    The virtual network option uses Network Address Translation (NAT) to share the default network device with the guest. Use the virtual network option for wireless networks.
    The shared physical device option uses a network bond to give the guest full access to a network device.
    Press Forward to continue.
  11. Memory and CPU allocation

    The Memory and CPU Allocation window displays. Choose appropriate values for the virtualized CPUs and RAM allocation. These values affect the host's and guest's performance.
    Guests require sufficient physical memory (RAM) to run efficiently and effectively. Choose a memory value which suits your guest operating system and application requirements. Most operating system require at least 512MB of RAM to work responsively. Remember, guests use physical RAM. Running too many guests or leaving insufficient memory for the host system results in significant usage of virtual memory. Virtual memory is significantly slower causing degraded system performance and responsiveness. Ensure to allocate sufficient memory for all guests and the host to operate effectively.
    Assign sufficient virtual CPUs for the guest. If the guest runs a multithreaded application, assign the number of virtualized CPUs the guest will require to run efficiently. Do not assign more virtual CPUs than there are physical processors or threads available on the host system. It is possible to over allocate virtual processors, however, over allocating has a significant, negative effect on guest and host performance due to processor context switching overheads.
    Press Forward to continue.
  12. Verify and start guest installation

    The Finish Virtual Machine Creation window presents a summary of all configuration information you entered. Review the information presented and use the Back button to make changes, if necessary. Once you are satisfied click the Finish button and to start the installation process.
    A VNC window opens showing the start of the guest operating system installation process.
This concludes the general process for creating guests with virt-manager. Chapter 8, Guest operating system installation procedures contains step-by-step instructions to installing a variety of common operating systems.
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