2.6. Comitting changes to a backing image
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2.6. Comitting changes to a backing image

Sometimes we would want to update a base-image to resemble the contents of an attached COW image. Maybe we wanted to make the latest system updates a part of the base image, or a configuration setting needed to be updated. This was as simple as making the base-image read-write, and running qemu-img commit on the created file.

[Important]Important

You should turn off or suspend the virtual machine when running the commit command. Failure to do so could result in data corruption.

Example 2.21. Commiting changes

# qemu-img create -f qcow2 /srv/base-images/base-image01.qcow2 10G
Formatting '/srv/base-images/base-image01.qcow2', fmt=qcow2 size=10737418240 encryption=off cluster_size=65536

# qemu-img create -b /srv/base-images/base-image01.qcow2 -f qcow2 /srv/images/with-backing-image.qcow2
Formatting '/srv/images/with-backing-image.qcow2', fmt=qcow2 size=10737418240 backing_file='/srv/base-images/base-image01.qcow2' encryption=off cluster_size=65536

# qemu-img commit /srv/images/with-backing-image.qcow2
Image committed.

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2.5. Creating Disks with Backing Images Home 2.7. Cloning a Physical Disk