In a recent blog post, Google announced machine images, which is a new type of Compute Engine resource containing all the information users need to create, backup, or restore a complete virtual machine (including multiple disks), and thus reducing the amount of time required for managing environments. The feature in Compute Engine is currently in beta, and not covered by any SLA or deprecation policy.
According to the announcement blog post, machine images can serve two purposes: machine backup, and creating golden machine images. When creating a backup with the machine images features it doesn’t just store the disk, it also stores other information such as machine type, network tags, and labels. With the older ‘custom images’ feature, the former was already possible; however, machine images can span multiple disks and contain instance properties of individual machines, instance metadata, and the relevant permissions.
Google Compute Engine product manager Ari Liberman states in the announcement blog post:
In addition to storing complete instance properties and data, machine images use the same differential disk backup technology that powers incremental snapshots, giving you fast, reliable and cost-effective instance backups.
Furthermore, machine images provide guarantee crash-consistency across all the attached disks at a given point in time and allow users to specify the location of the machine images.
Next to serving as a backup solution, users can leverage machine images to capture a particular configured image and store it as a golden machine image. Google recommends stopping the instance before creating the golden image to keep system integrity. Moreover, with a golden image, users can spin up as many instances in the way it was set or decide to share it with other projects. Furthermore, users can tweak the instance properties of the image by using the machine override functionality.
Users can use the machine images feature in Compute Engine through the Google Cloud Platform (GCP) console, gcloud or API. With the GCP console, users can choose the machine images option, select create a machine image, choose a VM-instance, specify a location, and encryption method.
Source: https://cloud.google.com/blog/products/compute/compute-engine-gets-machine-images
More details on machine images, including pricing information, is available on the online documentation.