techne/qemu.org

QEMU

• Take snapshot of VM
• Full disk backup of VM

Take snapshot of VM

sudo virsh domblklist vm1

Target          Source
-----------------------------------------------
vda             /var/lib/libvirt/images/vm1.img

sudo virsh snapshot-create-as \
        --domain vm1 \
        --name guest-state1 \
        --diskspec vda,file=/var/lib/libvirt/images/overlay1.qcow2 \
        --disk-only \
        --atomic \
        --quiesce

Ensure qemu-guest-agent is installed inside the VM. Otherwise omit the --quiesce flag, but when you restore the VM it will be as if the system had crashed. Not that big of a deal since the VM's OS should flush required data and maintain consistency of its filesystems.

sudo rsync -avhW --progress /var/lib/libvirt/images/vm1.img /var/lib/libvirt/images/vm1-copy.img

sudo virsh blockcommit vm1 vda --active --verbose --pivot

Full disk backup of VM

Start the guest VM:

sudo virsh start vm1

Enumerate the disk(s) in use:

sudo virsh domblklist vm1

Target          Source
-------------------------------------------------
vda             /var/lib/libvirt/images/vm1.qcow2

Begin the backup:

sudo virsh backup-begin vm1

Backup started

Check the job status. "None" means the job has likely completed.

sudo virsh domjobinfo vm1

Job type:        None

Check the completed job status:

sudo virsh domjobinfo vm1 --completed

Job type:               Completed
Operation:              Backup
Time elapsed:           182     ms
File processed:         39.250 MiB
File remaining:         0.000 B
File total:             39.250 MiB

Now we see the copy of the backup:

sudo ls -lash /var/lib/libvirt/images/vm1.qcow2*

15M -rw-r--r--. 1 qemu qemu 15M May 10 12:22 vm1.qcow2
21M -rw-------. 1 root root 21M May 10 12:23 vm1.qcow2.1620642185