When building a cloud, scale it out.

Cisco Intelligent Automation for Cloud architecture and topology options enable scalability, availability, and geographic distribution. This white paper discusses several options, their strengths and uses, and the technical details underlying these options."

Cisco IAC Availability, Scalability, and Geographic Distribution White Paper is available in the Cisco support community (log in needed)

Here's an excerpt:

Cisco Intelligent Automation for Cloud (IAC) is a software-based solution for managing hardware infrastructure tasked with delivering various IT services as-a-service (XaaS). Cisco IAC provides configuration "content" to help customers rapidly deploy service-delivered, self-service enabled IT services on certain hardware architectures. Consulting services from Cisco Advanced Services or Cisco delivery partners can use the IAC infrastructure to create custom services for customers. This white paper discusses the software underpinnings of these services and options for deployment that provide scalability and resilience for large enterprises or service providers.
The major platform products which make up IAC relevant to a scaling and resiliency discussion are:

• The Cisco Cloud Portal -The dynamic, tailored end-user web site where customers and administrators can browse available services and options, and order new services or changes to existing services. This element consists of a web tier which interacts with the browser to expose the Portal UI and an application tier which includes the Portal and Service Catalog. The Service Catalog provides the menu of available services, including new-service and update-service requests, as well as definitions and configurations for roles, business rules, dynamic form rules, and entitlement.
• Cisco Process Orchestrator  -The delivery engine that makes the Move/Add/Change/Delete (MACD) changes to the steady-state configuration of the computing, network, storage, and application infrastructure ("Infrastructure") needed to deliver the requested new service or service change. Orchestrator processes automate workflows which interact with applications, systems, and devices in the environment.
• A database stores configuration, state, and runtime information from the above systems.
• Cisco Network Services Manager (NSM) Server -a specialized engine for network provisioning. Cisco Network Services Manager's policy-driven approach allows clouds to be created within single or multiple network Points of Delivery (PoDs), each with potentially different and unique offerings and operational behaviors.
• Cisco NSM Controller -a local element near network devices within a network PoD which performs direct device interactions to achieve network provisioning at the direction of the NSM Server.
• Cisco Server Provisioner -provides bare metal provisioning (remote installation) of an OS or hypervisor on a physical or virtual server, as well as bare metal imaging for system cloning and backup.