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Devising the right hosting strategy: private, public or hybrid?

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While the cloud comes in many flavors, essentially organizations have a choice between three basic types of cloud deployment: private, public and hybrid. The key question is: how do organizations decide which cloud fits their strategy best? Rather than thinking of this as a strategic infrastructure-based decision, they should look at it from an application perspective.

While cloud adoption is the right goal, the split between private and public cloud can be misunderstood. Private cloud is often an easier adoption route than public cloud for many applications, while public cloud is a better option either for relatively self-contained applications, cloud native applications (purpose-built for cloud) or transformed applications. A hybrid cloud is the typical landscape which combines the benefits of private and public cloud environments.

About the author

Clive Grethe is Global Head of Hybrid Cloud – Telecoms, Media and Technology at Atos

New versus legacy applications

When developing new applications for digital transformation, organizations need to consider where they want the application to be hosted. As these new applications will usually be developed with cloud hosting in mind, they can thrive in both public and private cloud environments. Generally speaking, the public cloud will bring all the key advantages offered by the cloud: ease of deployment, standardization, agility, automatic scaling, and less concern around management and support.

Legacy applications, written in older languages or in the pre-cloud era, are an entirely different matter. They have almost all been developed without a cloud strategy in mind, and cloud deployment is therefore less obvious for these applications. Moving them to the cloud will require a careful consideration whether the advantages outweigh the inherent obstacles. As cloud technology continues to advance, more options will become available for legacy applications; so while a decision may not be viable today, it could be in 12 to 18 months.

Public cloud pros and cons

The true added value of the public cloud is in the applications written specifically for cloud environments or when using ‘Platform as a Service’ (PaaS) or ‘Software as a Service’ (SaaS) solutions. However, in the case of using the public cloud to host legacy applications in an ‘Infrastructure as a Service’ (IaaS) model, the public cloud offers no true value-add other than providing an evergreen and standardised environment.

Moving legacy to public cloud does not intrinsically change the application architecture. Or, to put it differently: the application is not becoming digital because it is running on Infrastructure as a Service; one simply moves the existing legacy from a legacy environment to a new computing environment, without reaping any cloud benefits.

Managing legacy applications

If organizations want these legacy applications to benefit from the public cloud environment, they should first redevelop them into a microservice container-based solution. Alternatively, these applications can be deployed on a private cloud until they get phased out and replaced by a cloud-native solution, or until technology advances to accommodate real legacy.

The value-add of keeping the legacy applications on a private cloud infrastructure is that private clouds can be more flexible in meeting the requirements for hosting legacy applications than the public cloud can.

Making application-based decisions

It can be tempting to set public or hybrid cloud as the default infrastructure solution. In truth, however, cloud isn't right for everything; for example, while it expands and shrinks very quickly, it is not good for high input-output activity, which requires faster throughput. Mainframes, high performance computing and private cloud solutions may be best in these cases.

Application latency is also a key driver; if some applications go to the public cloud and some remain behind, but each are dependent on each other, then this latency is likely to become a major technical issue. Again, technology continues to improve – but without modernizing at least some of these legacy applications, the applications will not be efficient.

Seamless user experience

Once applications are moved, users should have a seamless experience regardless of where their application is hosted. Providing that seamlessness experience while enabling a gradual migration of the legacy applications into cloud-native solutions is not an easy task. This gradual migration, or cloudification, can be a long journey and should be planned meticulously.

The most obvious conclusion can be summarised as follows: for the time being the best solution will always be some form of hybrid cloud, offering applications in the public cloud when advisable and keeping legacy applications in the private cloud until further notice.

Experience suggests that successful organisations adjust their transformation approach to place digital at the centre of their business agendas. Even where only a very high-level vision and strategy are established, and the Board relies as much on intuition as on empirical business cases, organisations can still embark on a successful transformation journey by hiring a trusted and experienced third party to accompany them. The most important decision is to get started.