You need to have seed first.

A Seed VM is a bootable KVM VM image provided as part of HP Helion OpenStack and is deployed in a VM instance. This image contains the minimum services required of OpenStack to function and to be able to provision physical hardware to deploy the Undercloud. The services are Nova, Neutron, Glance, Keystone, Ironic & Heat.

Undercloud: In simple - single node or all in one setup.

The Undercloud server is a basic, single-node, OpenStack installation running on a single physical server used to deploy, test, manage, and update the overcloud servers. There is no HA configuration for the Undercloud.

It contains a strictly limited sub-set of OpenStack, just enough to interact with the Overcloud. The services running on Undercloud are Nova, Neutron, Glance, Keystone, Ironic, Heat, Horizon & Ceilometer. This server also contains HP Helion content distribution catalog service, which provides a mechanism to download and install content and updates for the Overcloud.

The Undercloud also hosts images for various server types which will form the functional cloud environment - the Overcloud. These images are Overcloud Controller, Overcloud Compute, Overcloud Swift & Overcloud Compute Proxy (required for cloud which supports VMWare ESX as a hypervisor).

This is the second phase of the HP Helion OpenStack installation.

Overcloud:

The Overcloud is the functional cloud available to run guest virtual machines and workloads. It offers access to Nova, Neutron, Glance, Keystone, Cinder, Swift, Ironic, Heat, Horizon, and Ceilometer services.

Setting up the Overcloud completes the overall Helion Openstack installation process.