Create "linked clone" or layered shared disks with QEMU

Does QEMU support a feature like VMware's "linked clone"?

What I'm trying to accomplish: I'm setting up a test environment with a handful of VMs, that are all nearly identical. However, a fresh Windows install takes over 20 GiB, which would be duplicated for each VM.

In VMware, one would create a "linked clone", which is most likely a copy-on-write layer atop the original disk image.

Can we do this with QEMU? I'm specifically trying to accomplish this using virt-manager (libvirt).

Linked Cloning? (convirture.com)

QEMU's primary virtual disk format is QCOW2, which stands for QEMU Copy-On-Write 2. It is desiged specifically to enable these kinds of setups.

You can do this manually using qemu-img. (Skip directly to the second command if you already have a base image)

$ qemu-img create -f qcow2 base-image.qcow2 1M
Formatting 'base-image.qcow2', fmt=qcow2 size=1048576 encryption=off cluster_size=65536 lazy_refcounts=off refcount_bits=16

$ qemu-img create -f qcow2 -b base-image.qcow2 linked-image.qcow2
Formatting 'linked-image.qcow2', fmt=qcow2 size=1048576 backing_file='base-image.qcow2' encryption=off cluster_size=65536 lazy_refcounts=off refcount_bits=16

$ qemu-img info base-image.qcow2
image: base-image.qcow2
file format: qcow2
virtual size: 1.0M (1048576 bytes)
disk size: 196K
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16
    corrupt: false

$ qemu-img info linked-image.qcow2
image: linked-image.qcow2
file format: qcow2
virtual size: 1.0M (1048576 bytes)
disk size: 196K
cluster_size: 65536
backing file: base-image.qcow2
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16

Create "linked clone" or layered shared disks with QEMU

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