Instances are virtual machines that run in the cloud. You can start an instance from the following sources: Images uploaded to the OpenStack Image Service. See Managing Images for the Image Service. An image that you copied to a persistent volume. The instance starts from the volume, which the cinder-volume API provides through iSCSI. See Attaching a Volume to an Instance. Start an OpenStack Instance from an ImageWhen you start an instance from an image, OpenStack creates a local copy of the image on the compute node where the instance starts. You can observe OpenStack instances in vSphere as VMs, but you must manage them in OpenStack. Start an OpenStack Instance from a SnapshotYou can start an instance from an instance snapshot. You can observe OpenStack instances in vSphere as VMs, but you can only manage them in OpenStack. Connect to an Instance by Using SSH Track Instance UseYou can track use for instances in each project. You can view instance metrics such as number of vCPUs, disks, RAM, and uptime. Create a Snapshot from an InstanceWith snapshots, you can create new images from running instances. Using Affinity and Anti-Affinity to Place OpenStack InstancesThe Nova scheduler provides filters that you can use to ensure that OpenStack instances are automatically placed on the same host (affinity) or separate hosts (anti-affinity).