1. KVM User's Guide
  2. KVM Instances: Create and Manage
  3. Clone: Existing KVM Instance

Clone: Existing KVM Instance

System administrators can easily create a KVM instance by cloning the configuration of an existing KVM instance. Depending on the use of the clone, system administrators can either prepare the source KVM configuration before cloning it, or simply create a KVM clone with the identical configuration as the source KVM instance.

Note:

When creating multiple clones from a single KVM instance, we recommend preparing the source configuration before cloning it. Preparing the source configuration lets you examine the configuration and remove unique parameters that would not apply to the clone configuration and cause the clone to possibly fail or not work correctly.

For instructions on how to prepare a KVM instance for cloning or create a KVM clone, see these topics:

Note:

In addition to using the CLI to create KVM clones, you can use the Cockpit web console to clone KVM instances. For details, see Cloning VMs in Oracle Linux: Using the Cockpit Web Console.

Prepare KVM for Cloning: Using virt-sysprep

The following information describes how to use the system preparation scripting tool (virt-sysprep) to prepare a source KVM disk configuration for cloning.

Note:

The virt-sysprep tool helps you to prepare a KVM configuration for cloning by removing SSH host keys, persistent network configurations, and user accounts on the disk image. It also lets you add SSH keys, users, or logos. For more details about virt-sysprep, see https://libguestfs.org/virt-sysprep.1.html.
What Do You Need?
  • All important data on the source KVM is backed up.

    Note that virt-sysprep changes the disk image in place without making a copy of it. To keep the configuration of the source KVM intact, create a clone. For details, see Create a KVM Clone Using virt-clone Command.

  • The system preparation tool (virt-sysprep) must installed on the host. 
    yum install /usr/bin/virt-sysprep
  • The source KVM must be shut down.
  • The location of the source KVM disk image is required. Also, you must be the disk image owner and have disk write permissions.

Follow these steps to use the virt-sysprep tool to prepare a source KVM disk image configuration for cloning.

  1. Log in as the root owner of the KVM disk image, for example: 
    whoami
root
  2. To prepare the source KVM disk image for cloning, use the following virt-sysprep command syntax. 
    virt-sysprep -a [/var/lib/libvirt/images/a-replace me -my-kvm.qcow2]
[   0.0] Examining the guest ...
[   7.3] Performing "abrt-data" ...
[   7.3] Performing "backup-files" ...
[   9.6] Performing "bash-history" ...
[   9.6] Performing "blkid-tab" ...
[...]
    Where:
    • [/var/lib/libvirt/images/replace me-my-kvm.qcow2] replace with the source KVM disk image path.
  3. Use the virt-sysprep tool to inspect the prepared disk image. For a list of available options, type: virt-sysprep --help
    For more details, see the virt-sysprep(1) Linux man page.
  4. After preparing the disk image for cloning, proceed with using the prepared KVM disk configuration to create a clone.
    For details, see Create a KVM Clone Using virt-clone Command.

    Note:

    On the first boot of the clone, we recommend that you change the hostname.

Prepare KVM for Cloning: Manually

The following information describes how to manually prepare a source KVM configuration for cloning.
What Do You Need?
  • All important data on the source KVM is backed up.

    To keep the configuration of the source KVM intact, create a clone. For details, see Create a KVM Clone Using virt-clone Command

  • The location of the source KVM disk image is required. Also, you must be the disk image owner and have disk write permissions.
  • The source KVM must be shut down.
  • Administrator privileges.

Follow these steps to manually prepare a source KVM configuration for cloning.

  1. Configure the source KVM as required, for example:

    • Install any required software for clone.

    • Configure any required properties that are considered non-unique for the operating system or system applications.

  2. Remove the network configuration, as follows:
    1. To remove any persistent udev rules, type:
      rm -f /etc/udev/rules.d/70-persistent-net.rules

      Note:

      If you don't remove the udev rules, the name of the first NIC might be eth1instead of eth0.

    2. Change /etc/sysconfig/network-scripts/ifcfg-eth[x] to remove the HWADDR and static lines and any other unique or non-desired settings, such as UUID, for example: 

      DEVICE=eth[x]
BOOTPROTO=none
ONBOOT=yes
#NETWORK=10.0.1.0       <- REMOVE
#NETMASK=255.255.255.0  <- REMOVE
#IPADDR=10.0.1.20       <- REMOVE
#HWADDR=xx:xx:xx:xx:xx  <- REMOVE
#USERCTL=no             <- REMOVE

      After modification, the file must not include a HWADDR entry or any unique information, and at a minimum include the following lines: 

      DEVICE=eth[x]
ONBOOT=yes

      Important:

      You must remove the HWADDR entry because if its address doesn't match the new guest's MAC address, the ifcfg is ignored.

    3. If the following files exist, ensure they have the same content:
      • /etc/sysconfig/networking/profiles/default/ifcfg-eth[x]
      • /etc/sysconfig/networking/devices/ifcfg-eth[x]

      Note:

      If NetworkManager was used or any special settings with the KVM, ensure that all unique information is removed from the ifcfg scripts.
  3. Remote ULN registration details.
    For example, if the KVM guest from which you want to create a clone is registered with ULN, you must unregister it. For more information, see the applicable reference:
  4. Remove sshd public/private key pairs.
    For example, type: 
    rm -rf /etc/ssh/ssh_host_[name]
  5. Remove any other application-specific identifiers or configurations that might cause conflicts if running on multiple machines.
  6. Configure the relevant setup configuration wizard to run at first boot.
    Examples:
    • For Oracle Linux 7, enable the first boot and initial-setup wizard: 
      sed -ie 's/RUN_FIRSTBOOT=NO/RUN_FIRSTBOOT=YES/' /etc/sysconfig/firstboot
systemctl enable firstboot-graphical
systemctl enable initial-setup-graphical
    • For Oracle Linux 8 and 9, remove the gnome-initial-setup-done file to configure the KVM to run the configuration wizard on the next boot:
      # rm ~/.config/gnome-initial-setup-done
  7. After addressing all required modifications, proceed to using the prepared KVM configuration to create a clone.
    For details, see Create a KVM Clone Using virt-clone Command.

    Note:

    On the first boot of the clone we recommend that you change the hostname.

Create a KVM Clone Using virt-clone Command

The following information describes how to clone a source KVM instance using the virt-clone command.
What Do You Need?

Steps

Follow these steps to clone an existing KVM instance:

  1. Perform one of the following:
    • To clone a source KVM with its original configuration, use the following virt-clone command syntax: 
      virt-clone --orginal kvm-name --auto-clone
      For example, if you typed: 
      virt-clone --orginal My_KVM --auto-clone
      Output similar to the following appears:
      virt-clone --original My_KVM --auto-clone
Allocating 'My_KVM-clone.qcow2'                            | 55.0 GB  00:02:37

Clone 'My_KVM-clone' created successfully.
      In this example, the virt-clone command copies the source My-KVM configuration and creates: (1) a clone KVM guest named My_KVM-clone, and (2) a clone disk image named My_KVM-clone.qcow2

      -OR-

    • To clone a source KVM using the virt-clone command with other options, type the following command to view the available configuration options: 
      virt-clone --help
      For more examples of how to use the virt-clone command, see the virt-clone(1) Linux man page.
  2. Verify that the cloned KVM instance is working, for example:
    • Confirm that the clone has been added to the list of KVMs on the host:
      virsh list --all
Id   Name                  State
---------------------------------------
-    My_KVM          shut off
-    My_KVM-clone    shut off
    • Start the clone and observe if it boots up:
      virsh start My_KVM-clone
Domain 'My_KVM-clone' started