OpenStack:Glance

Glance

Glance provides a catalog and repository for virtual disk images. It allows you to store and retrieve VM images, along with all the required metadata.

Images

A virtual disk image is a file that contains a bootable operating system. An Instance is launched from an image, and many instances can use the same image. This is because the instance does not change the image.

The root disk of each instance by default resides on ephemeral (short term) storage - for piston this will be a logical volume on a single cloud node. Optionally an instance can be booted from a cinder volume which for piston will exist on three cloud nodes.

Snap Shots

A Snapshot of running is a copy of the data contained within an instance. It is useful as backups, or to create a customized image.