Cloud Deployment Models

A cloud deployment model can be described as a distinct parameterized configuration of the cloud computing environment. These parameters include storage size, ownership and accessibility.

There are four main cloud deployment modes:

  • public,
  • private,
  • hybrid, and
  • community

Web-based organization systems like the inter-cloud and virtual private are also two other emerging deployment models but yet to gain widespread popularity. Choosing the right cloud deployment model depends on the business, storage, networking and computing requirements of an organization.

Public Cloud

A public cloud, also known as an external cloud, is a cloud environment.

Ownership : Possession of a third-party cloud service provider.

Public cloud platforms are fully owned and maintained by a third-party cloud service provider, creating virtual machines (VMs) for use.

Accessibility : Publicly accessible (open access).

Public cloud models in which cloud computing services are provided and accessed over a public network (with permission) such as the internet.

Storage size :  Huge storage size.

Public cloud storage enables individuals and organizations to store, edit and manage huge storage amount of data. This type of storage exists on a remote cloud service provider server and is accessible over the internet. A cloud service provider hosts, manages and sources the storage infrastructure publicly to many different users.

The data and application in the public cloud are created and retained on third-party servers for general public access and use. Provisioning of resources is done dynamically by the off-site third-party cloud service provider and offers access to these resources via a web application or a web service or over the internet as shown in the figure below.

structure of public cloud

The other responsibilities include the administration and maintenance of the pool resources and the entire cloud infrastructure is done by the cloud service provider.

This way, public cloud consumers are relieved of the cost of application, bandwidth and hardware acquisition and maintenance requirements in their daily business operations.

However, the public cloud subscriber (consumer) is offered a pay-as-you-go fine-grained utility pricing model that ensures that the billing is made only for services used and for the period of the usage.

In other words, the utility pricing model ensures that the consumer pays only for the amount of shared resources used within a stipulated amount of time. This makes the public cloud very economical and easy to use.

Examples of public cloud include Rackspace, Amazon Elastic Compute Cloud (Amazon EC2), Sun Cloud, IBM’s Blue Cloud, Windows Azure Services Platform, and so on.

Characteristics of Public Cloud

  • Resources are homogenous
  • Operates a common administrative control and privacy policies
  • Multitenancy and shared resources
  • Leased or rented cloud resources
  • Economies of scale

Advantages of Public Cloud

  • Easy setup and use
  • Easy data accessibility
  • Flexibility to add and reduce required capacity
  • Continuous operation time
  • 24/7 upkeep
  • Cost effectiveness
  • Saves cost of procuring software and updates

Disadvantages of Public Cloud

  • Data privacy and security
  • Compromised reliability
  • The lack of administrative power
  • Third-party data access

Private Cloud

The private cloud can also be described as an internal cloud. Some also refer to it as a corporate cloud. The private cloud is a cloud environment.

Advantages of Private Cloud

  • Ownership : A private cloud model provides the total ownership that is equal to total control. This is the strength of the private cloud. This type of cloud is managed by a single (specific) organization and cloud service provider.
  • Accessibility : A private cloud model has controlled/limited access (only for clearly defined set of persons). A private cloud model is a cloud model in which cloud computing services are provided and accessible over a private network (with permission) such as the internet.
  • Storage size : Limited storage; in a private cloud model, computing resources are dedicated to serving a single organization. This means the software

A private cloud only permits limited access because its highly-virtualized data center architectures are housed by the organization’s firewall, making it less risky.

In the same vein, it also allows consumers to define and set their preferred customized privacy policies and security requirements.

These features make it far more secured than the public cloud. However, unlike the economical public cloud, a private cloud is capital intensive as it requires some capital to buy, build an manage.

Some examples of a private cloud include Simple Storage Service (S3), Red Hat, SaM Cloudbox and Amazon EC2.

A private cloud has many advantages and certain limitations which are summarized in the following table:

Advantages of Private Cloud Disadvantages of Private Cloud
Computational resources and network access is made available to users Not economical : Incurs considerable cost of hardware, software and staff training
Customizable network and storage and components Not financially feasible to adopt by small and medium organizations
Greater control over the corporate cloud information
High privacy, security and reliability : That is, it can safeguard mission-critical operational data/sensitive data
Maximum level of scalability

Hosting of a private cloud server is done on-premise or externally:

On-premise private cloud

On-premise private cloud also referred to as internal cloud is hosted within an organization’s own data center as shown in the figure below.

On-premise private cloud

On-premise private cloud

It provides a more standardized process and security but is often limited in scalability and size. Operational and capital costs for the organization’s physical resources are incurred by the organization. The internal cloud is best used for applications that require complete control and configurability of the infrastructure and security:

Externally-hosted private cloud

The private cloud server is hosted externally and within an exclusive privacy and data security guarantee facilitated by a cloud provider as presented in the figure below.

Out-sourced private cloud

Out-sourced private cloud

It shields the organization from undue risks associated with the sharing of physical resources as seen in the public cloud. Technically, the external cloud, including the pool of resources and infrastructure, is made exclusively for the subscriber by partitioning and separating the private solution from the entire resources of the cloud service provider.

General characteristics of a private cloud

  • Self-service resource provisioning and compute capability
  • Automated and well-managed virtualized environments
  • Optimized computing resources and servers’ utilization
  • Support specific workloads
  • Heterogeneous and dedicated infrastructure
  • Customized policies and end-to-end control

Hybrid Cloud

A hybrid cloud environment integrates the operational characteristics of two or more public and private clouds such that some part of the organization’s resources are partially hosted within the organization and the rest are hosted externally in a public cloud.

A typical structure of a hybrid cloud is presented in the figure below.

structure of a hybrid cloud

Structure of a Hybrid cloud

The integration follows a standardized technology that ensures application and data portability. However, with this deployment model, a private cloud could be used to process sensitive (critical) cloud services while other auxiliary cloud service tasks are outsourced to the public cloud.

It is often used for backup purpose and to keep records due to its high scalability and cost-effectiveness.

Advantages and Disadvantages of Hybrid Cloud

Advantages of Hybrid Cloud Disadvantages of Hybrid Cloud
Enhanced privacy and security Complex maintenance of two or more deployment architectures
Greater flexibility and scalability Disparity in cloud environments
Reasonable price Split responsibilities between the private cloud provider organization and the public cloud provider

Community Cloud

This cloud environment is similar to a private cloud except for the ownership of the cloud resources and infrastructure.

Using a community cloud, several organizations with very similar technical and business-specific requirements and objectives can jointly share the cloud resources and infrastructure.

It can be described as a close private cloud for some specific set of mutual users. A community cloud is characterized by centralized multi-tenant data center architecture, facilitating easy and efficient project initiation, development, management and implementation.

However, it offers high cost savings because it is shared among all the cooperating users in the community cloud. Some examples of community clouds include Google Government Cloud, IGT Cloud, Optum Health Care Cloud, and so on.

Similar to a private cloud, a community cloud can also be hosted internally or externally.

Outsourced community cloud

In this arrangement, the server is outsourced to a cloud service provider. However, the infrastructure of an outsourced community cloud exists off-premise and is configured to serve a number of companies that request and use cloud services.

A structure of an outsourced community cloud is represented in the following figure.

Out-sourced community cloud

Out-sourced community cloud

On-site community cloud

The cloud infrastructure is accessed and used by several companies in the same cloud community having similar and closely-related shared concerns, including privacy and security requirements, compliance considerations and policies.

In the following figure, a structure of an on-site community cloud is shown.

On-site community cloud

On-site community cloud

Advantages of Community Cloud Disadvantages of Community Cloud
Cost reduction Higher cost than that of a public one
Improved security, privacy and reliability Sharing of fixed storage and bandwidth capacity
Ease of data sharing and collaboration Broad adoption is slow