Deployment models

Deployment models are different types of cloud computing. The cloud service models are deployed in different ways, based on the consumer’s preference. Mell and Grancs (2011) defines four types of these deployment models in cloud computing. They are Public cloud, Private cloud, Hybrid cloud and Community cloud. These are the principal cloud service delivery models, which enables the cloud service provider to provision scalable IT resources like CPU or storage or software development environment or software applications (Furht and Escalante, 2010). The service models help the consumer to decide what type of service they need, whereas deployment models help the consumer to know

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the location and the purpose of the cloud (Sosinsky, 2011). Though all the three deployment models offer similar benefits like cost-efficiency, performance, scalability and reliability, it is up to the consumer to choose the deployment model based on their business needs (Azure.microsoft.com, 2019).

6.5. 1 Public cloud

This is the first deployment model that gained the attention of IT for its ease of usage, availability, scalability and reliability. This public cloud infrastructure is generally provisioned by either a business or an academic or a government organisation to the general public or a large industry group (Linthicum, 2010).

Since this public cloud is owned, managed and operated by a third-party cloud service provider, the infrastructure exists on the premises of the provider (Mell and Grancs, 2011). The service provided in this type of cloud is described as a “utility”, because the consumers use the service on a pay-as-you-go model (Sosinsky, 2011). Public cloud is also called as external cloud, as the third-party service provider who is off-site, dynamically provision the computing resources to the consumer through web services (Xing and Zhang, 2012). The resources in this public cloud are shared by the consumers, where the maintenance of the infrastructure is the responsibility of the provider.

Deployment of public cloud is much quicker than on-premises infrastructure and it is infinitely scalable as it can collaborate higher level of resources.

Public cloud allows multi-tenancy because employees from an enterprise can access the same resource (application, storage, server…) from any branch distributed in different geographical locations, using any device, with the only requirement of being connected

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to the internet. It is cost-effective as it charges the consumers on a pay-as-you-use basis (Dataflair team,2018).

With efficient security methods being implemented, and effectively managed, the public cloud could be as secure as possible, like a private cloud (Azure.microsoft.com, 2019).

This deployment model is best suited for globally distributed teams of an enterprise, as public cloud enables them to easily access the centrally managed infrastructure with a connection to the internet (Shroff ,2010).

6.5. 2 Private cloud

This deployment model is best suited for a single organization, where the cloud can be owned, managed and operated by the organization itself or in combination with a third party. The private cloud can be on the premises or off the premises (Mell and Grancs, 2011). In the private cloud the data is under the control of the single entity, for example CaaS (Compliance as a Service) system is built in a private cloud, where the data is under the control of the entity, including the transactions being monitored (Sosinsky, 2011).

Private cloud enables an individual organisation to maximize the usage of its computing resources and be more flexible and responsive to the company needs, which is not feasible in the legacy IT operating model (Hugos and Hulitzky, 2011).

Firms can build their private cloud data centre in their heterogeneous corporate environment, according to their business needs to leverage existing IT infrastructure and use them in a more cost-effective way. The private cloud eliminates issues like data security, regulatory compliance issues that would arise in a public cloud.

Private cloud would best suit the companies like health care firms, which handle sensitive data that are not be shared in the public platform. Private cloud allows the firms to try and test the reliability of the cloud adoption in a private mode and then move onto the public

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cloud infrastructure in the future to save the cost. Private cloud may suit the firms which has proprietary applications that cannot be used in a shared platform, outside their own or their sister concerns which are geographically apart (Leapfrog IT Services, 2019). The hassles involving Service Level Agreement (SLA), data security, regulatory compliance could be eliminated in private cloud, as they are located on-premises of the consumer (Hugos and Hulitzky, 2011).

6.5. 3 Community cloud

Community cloud can be thought of as a public cloud, with the level of privacy, security and regulatory compliance similar to that of a private cloud (Kleyman, 2014). This deployment model is provisioned for an exclusive usage by consumers that belong to a community from firms with same concerns, mission, security requirement, policy and compliance considerations. Community cloud may be owned, managed, operated by a third-party cloud service provider either on their own or in combination with one or more of the firms in the community. This deployment model can be implemented on-premises or off-premises (Mell and Grancs, 2011).

Community cloud would suit the group of organizations that have same security concerns.

Though these communities may be benefited more from adopting public cloud deployment model, they will have less worry about the neighbour with whom they are sharing the resources in the community cloud, as the firms that belong to the same community know each other (Williams, 2010).

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6.5. 4 Hybrid cloud

This deployment model blends the characteristics of both public and private cloud. The cloud services are provided in public and private mode as per the need of the consumer.

The consumer might choose to hold the sensitive data in the private cloud and gain access to common applications, storage from the public cloud, which is cost effective than private cloud (Furht and Escalante, 2010).

For example, an organisation can use the public cloud as an overflow for the private cloud, where less-critical workloads can be moved to off-premise public cloud dynamically to manage unpredictable load demands. A hybrid cloud may combine multiple clouds like public, private and community where the unique identities of the clouds are retained in spite of being bound together. A hybrid cloud can provide proprietary or regular standardized access to the resources along with portability (Mell and Grancs, 2011).