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I want to back up a virtual machine image when I went to the directory where the images are stored /var/lib/libvirt/images/ I found one .img file, the rest were .qcow2, unlucky the virtual machine I want to back up is the one with the .qcow2 image. I'm not too sure what type of format that is also I'm not too sure if I compress this format if it would back up all of my data. Are you familiar with format, is my data stored in the .qcow2 file?

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To backup a qcow2, you have to quisece the filesystem (if it's running and qemu-guest-agent is running on the guest) and convert it to raw.

# qemu-img convert -O raw qcow2image.vm convertedraw.vm

When you want to restore it, you have to convert it back. Reverse order, changing the -O switch's value.

# qemu-img convert -O qcow2 convertedraw.vm qcow2image.vm

If the VM is running and you want to take a backup, these are the steps:

  1. Freeze the vm.
  2. Create a snapshot.
  3. Thaw the guest.
  4. Take a backup from the snapshot.

Like so.

# virsh domfsfreeze vmname
# qemu-img create -f qcow2 -b qcow2image.vm qcow2.snap
# virsh domfsthaw vmname
# qemu-img convert -O raw qcow2.snap backup.img

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