Taking Snapshots

The OpenStack snapshot mechanism allows you to create new images from running instances. This is very convenient for upgrading base images or for taking a published image and customizing it for local use. To snapshot a running instance to an image using the CLI, do this:

$ nova image-create <instance name or uuid> <name of new image>

The dashboard interface for snapshots can be confusing because the Images & Snapshots page splits content up into several areas:

  • Images

  • Instance snapshots

  • Volume snapshots

However, an instance snapshot is an image. The only difference between an image that you upload directly to the Image Service and an image that you create by snapshot is that an image created by snapshot has additional properties in the glance database. These properties are found in the image_properties table and include:

name value

image_type

snapshot

instance_uuid

<uuid of instance that was snapshotted>

base_image_ref

<uuid of original image of instance that was snapshotted>

image_location

snapshot

 Live snapshots

Live snapshots is a feature that allows users to snapshot the running virtual machines without pausing them. These snapshots are simply disk-only snapshots. Snapshotting an instance can now be performed with no downtime (assuming QEMU 1.3+ and libvirt 1.0+ are used).

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