The OpenStack Image Service enables users to discover, register, and retrieve virtual machine images. Also known as the glance project, the Image Service offers a REST API that enables you to query virtual machine image metadata and retrieve an actual image. Virtual machine images made available through the Image Service can be stored in a variety of locations from simple file systems to object-storage systems like OpenStack Object Storage. For simplicity this guide configures the Image Service to use the file backend. This means that images uploaded to the Image Service will be stored in a directory on the same system that hosts the service. By default this directory is /var/lib/glance/images/. Ensure that the system has sufficient space available under this directory to store virtual machine images and snapshots before proceeding. At an absolute minimum several gigabytes of space should be available for use by the Image Service in a proof of concept deployment.