A massively scalable architecture is a cloud implementation that is either a very large deployment, such as a commercial service provider might build, or one that has the capability to support user requests for large amounts of cloud resources. An example is an infrastructure in which requests to service 500 or more instances at a time is common. A massively scalable infrastructure fulfills such a request without exhausting the available cloud infrastructure resources. While the high capital cost of implementing such a cloud architecture means that it is currently in limited use, many organizations are planning for massive scalability in the future. A massively scalable OpenStack cloud design presents a unique set of challenges and considerations. For the most part it is similar to a general purpose cloud architecture, as it is built to address a non-specific range of potential use cases or functions. Typically, it is rare that particular workloads determine the design or configuration of massively scalable clouds. The massively scalable cloud is most often built as a platform for a variety of workloads. Because private organizations rarely require or have the resources for them, massively scalable OpenStack clouds are generally built as commercial, public cloud offerings. Services provided by a massively scalable OpenStack cloud include: Virtual-machine disk image library Raw block storage File or object storage Firewall functionality Load balancing functionality Private (non-routable) and public (floating) IP addresses Virtualized network topologies Software bundles Virtual compute resources Like a general purpose cloud, the instances deployed in a massively scalable OpenStack cloud do not necessarily use any specific aspect of the cloud offering (compute, network, or storage). As the cloud grows in scale, the number of workloads can cause stress on all the cloud components. This adds further stresses to supporting infrastructure such as databases and message brokers. The architecture design for such a cloud must account for these performance pressures without negatively impacting user experience.