Chapter 3 – Cloud Deployment and Delivery Models
For the enterprises, the most attractive factor of cloud is its flexible sourcing options and the choices of deployment. And again the different deployment and delivery models can co-exist and it is possible to integrate with traditional IT systems and with other clouds.
Cloud Delivery Models
The key delivery models for cloud are discussed below.
Private Cloud refers to IT capabilities are provided “as a service,” over an intranet, within the enterprise and behind the firewall. Privately owned and managed. The access limited to client and its partner network. The Private cloud drives efficiency, standardization and best practices while retaining greater customization and control within the organization. In a private cloud environment, all resources are local and dedicated. All cloud management is local.
Figure 1 Private Cloud
Public Cloud refers to IT activities / functions are provided “as a service,” over the Internet Service provider owned and managed. In public cloud, access is by subscription.
The public cloud delivers select set of standardized business process, application and/or infrastructure services on a flexible price per use basis. Multiple tenancy is a key characteristic of public cloud services.
Figure 2 Public Cloud
Hybrid cloud is a combination of characteristics of both public and private cloud where internal and external service delivery methods are integrated. For example in the case of an Off-Premise Private Cloud, resources are dedicated, but off-premise. Enterprise administrator can manage the service catalog and policies. Cloud provider operates and manages the cloud infrastructure and resource pool.
Figure 3 Off-Premise Private Cloud
Community cloud – This is the model where the cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be managed by the organizations or a third party and may exist on premise or off premise.
Public vs. Private trade-off considerations
Overall private clouds have higher levels of consideration than public clouds with most of the enterprises but there are various other models that are emerging.
Figure 4 Cloud Delivery Models
We need to balance the business benefits of increased speed and lower cost with public cloud offerings versus the security and ownership of infrastructure and service management considerations while choosing between a public and private cloud offering for a capability. The governance model, resiliency, level and source of support, architectural & management control, compliance, customization / specialization etc are other considerations.
Public and Private Clouds are preferred for different workloads. Many enterprises still prefer to host their traditional applications out of their private cloud. The top private workloads include
- Data mining, text mining, or other analytics
- Data warehouses or data marts
- Business continuity and disaster recovery
- Long-term data archiving/preservation
- Transactional databases
- Industry-specific applications
- ERP applications
As and when a workload becomes more standard and the SLAs are well established, the same service becomes easy to consume over a public cloud. This is similar to how you can access well defined banking functions through ATMs. Only when you need some special services you go to your bank these days. Similarly top public workloads include
- Audio/video/Web conferencing
- Service help desk
- Infrastructure for training and demonstration
- WAN capacity, VOIP Infrastructure
- Test environment infrastructure
- Data Centre network capacity
Cloud Deployment Models
All the computing related functions that clouds provide are accessed through a service catalog and delivered as integrated services. The different layers of IT-as-a-Service are referred to as the Cloud Deployment Models. More details of these definitions can be found at the NIST website which is source for some of the text below.
Figure 5 Cloud Deployment Models
Infrastructure as a Service (IaaS) is the service delivery model where customers use processing (server), storage, networks and other computing resources/ data center functionality. Iaas has the ability to rapidly and elastically provision and control resources. In this model customers can deploy and run software and services without the need to manage or control the underlying resources. The IBM Research Compute Cloud (RC2) is an example for this model. Smart Business Desktop on the IBM Cloud is another example for IaaS that enables desktop virtualization with a subscription service with no upfront fees or capital expense. Consider reading about IBM Cloudburst if you are building your own IaaS platform.
Platform as a Service (PaaS) is the delivery model where customers can use programming languages, tools and platforms to develop and deploy applications on multi-tenant shared infrastructure with ability the to control deployed applications and environments. All of these again can be done without the need to manage or control the underlying resources. IBM BPM BlueWorks provides tools to build your own business process. WebSphere Cloudburst is also something for you to look at if you building a PaaS yourself.
Software as a Service (SaaS) is the popular model where customers use applications (Eg, CRM, ERP, E-mail) from multiple client devices through a Web browser on multi-tenant and shared infrastructure without the need to manage or control the underlying resources. An example of this model is IBM lotuslive.
Business Process as a Service (BPaaS) is an emerging model where customers can consume business outcomes (Eg, payroll processing, HR) by accessing business services via Web-centric interfaces on multi-tenant and shared infrastructures. Smart Business Expense Reporting on the IBM Cloud is one of the offerings in this category.