Chapter 21. Backing up and recovering virtual machines

Procedure

1. Save the XML configuration of the VM to a separate file. For example, to save the configration of the testguest1 VM to the /home/backup/testguest1-backup.xml file, use the following command:

   # virsh dumpxml testguest1 > /home/backup/testguest1-backup.xml

2. Optional: Customize your backup settings. By default, libvirt creates copies of all disks in the VM in the same directory as the original disks. If you want to use a different configuration for your backup, create an XML file with your required settings. For example:

   <domainbackup>
     <disks>
       <disk name='vda' backup='yes'/>
       <disk name='vdb' type='file'>
         <target file='/home/backup/vdb.backup'/>
         <driver type='raw'/>
       </disk>
       <disk name='vdc' backup='no'/>
     </disks>
   </domainbackup>

   This example configuration ensures that the vda disk is backed up by using the libvirt defaults, the vdb disk is backed up in the raw format as /home/backup/vdb.backup, and that the vdc disk is not backed up.

3. Start the VM.

   # virsh start <vm-name>

4. Back up the disks of the VM by using the virsh backup-begin utility. The following command uses the default backup settings, which creates copies of all disks that the VM uses, and saves them in the same directory as the original disks

   # virsh backup-begin <vm-name>

   Optionally, to apply custom backup settings, you can specify the backup XML configuration that you created previously.

   # virsh backup-begin <vm-name> --backupxml <backup-XML-location>

Verification

1. Ensure that the backup operation has completed.

   # virsh domjobinfo <vm-name> --completed

   Example successful output:

   Job type:         Completed
   Operation:        Backup
   Time elapsed:     20704 ms
   File processed:   40.000 GiB
   File remaining:   0.000 B
   File total:       40.000 GiB

2. Check the target location of the backup disks. For example, if you used the default backup configuration and the VM disks are located in the default /var/lib/libvirt/images/ directory, use the following command:

   # ls -l /var/lib/libvirt/images

   Example successful output:

   -rw-------. 1 qemu qemu 42956488704 Oct 10 15:49 RHEL_10_beta.qcow2
   -rw-------. 1 root root 42956488704 Oct 29 16:12 RHEL_10_beta.qcow.21761750144
   -rw-------. 1 qemu qemu      196688 Oct 10 15:49 extra-storage.qcow2
   -rw-------. 1 root root 196688 Oct 29 16:12 extra-storage.qcow2.1761750144

Procedure

1. Inspect the backup XML configuration of the VM for the specific storage settings.

   # cat </path/to/backup.xml>

   Example output section:

   <disk type='file' device='disk'>
         <driver name='qemu' type='qcow2' discard='unmap'/>
         <source file='/var/lib/libvirt/images/vm-name.qcow2' index='3'/>

2. Move the backup disks to the locations specified in the backup XML and ensure that their names correspond with the values in the XML.

3. Define a new VM based on the backup XML.

   # virsh define --file </path/to/backup.xml>

4. Optional: Modify the XML configuration of the newly created VM to adjust for settings that might be different from the original host, such as the network.

   # virsh edit <vm-name>