If a company has decided to move its processes, applications and data into the cloud, it has to choose which infrastructure to use and how the apps and data will be hosted and distributed.
Companies moving into the cloud first have to consider how critical the data and applications they wish to move are to their business. They also must consider any regulatory or data protection requirements relevant to their organization.
In addition, they have to think about how applications will perform when transported over a network and assess how integrated cloud applications have to be with other corporate functions.
Private cloud infrastructures
Private clouds are built around infrastructures that are solely deployed on behalf of a single organization, although they could be managed internally and hosted externally by a third party.
They usually involve both internal management teams and the IT department becoming well entrenched in their design and ongoing development, with key decisions being made about how existing resources are re-allocated in the cloud.
Private clouds can often offer enhanced and tighter security, and more predictable availability for users supported by more fault tolerant network backbones, which can sometimes be lacking when public and shared cloud networks are used.
The cost of private clouds
That said, as private clouds are usually large dedicated infrastructures built for a single organization, by their very nature they can involve significant investments to get off the ground.
With private clouds, organizations install their own servers and storage hardware and have the flexibility to shift workloads among those servers as they see spikes in usage or when they deploy new applications.
Private clouds are often suited for businesses that have to comply with very strict industry regulations or data protection regimes, particularly when it comes to storing mission critical customer data.
Organizations in the financial or healthcare sectors often choose to go down the private cloud route.
Air France opts for private cloud
One company not in these sectors that has recently plumped for a substantial private cloud is Air France. The company says it has automated and increased the reliability of its 1,500 Linux servers by deploying a private cloud solution.
The deployment is based on HP's Cloud Service Automation (CSA) software to accelerate deployment times for physical and virtual infrastructures.
With between 350 and 500 installations and re-installations annually, Air France says its Linux server farm is growing rapidly.
With the resource costs incurred by these installations, it became necessary to standardize on a single tool to automate the deployment of operating systems, middleware, monitoring tools and capacity management.
The HP solution has significantly reduced the time it was taking to bring environments into service "while improving quality and reducing operational costs," said Air France.
"Since automating our installation processes, we have gone from around six days for installing a server cluster to one day and, instead of more than 24 hours, it now takes less than 15 minutes to install one virtual machine," said Patrick Bourel, head of open systems at Air France.
While the firm says its private cloud paid for itself within a year, public cloud services usually promise even shorter term economies.
Public cloud infrastructures
Most of us use public cloud services every day. Whether in the form of web email like Hotmail, Gmail or Yahoo, social media sites like Facebook or Twitter, or basic Internet browsing, we tend to trust web service providers with our personal data in the public cloud without much thought.
A business using the public cloud for its corporate apps and data must have the same confidence about it, but must also put a lot more thought into the security of the data and how it can efficiently access it.
That said, it's not as if the the cloud is more susceptible to security breaches. At least, that's providing both the cloud user and the cloud provider can make sure the servers and other hardware storing the data are secure, and that the networks the data travels on are protected.
The main difference between private and public cloud infrastructures is that a public cloud provider will use its infrastructure to house and distribute data for multiple organizations, not just yours.
The cost of public clouds
That's why public clouds usually work out cheaper than you buying the dedicated hardware for a private cloud just for your data, which also needs managing and updating by you - creating more costs.
The servers and other hardware in a public cloud are hosted off your premises and enable you to rent capacity in a scalable "pay-as-you-go" way in response to your business needs.
By delivering such economies of scale, public cloud systems are suitable for organizations needing temporary added data capacity at peak times or for special ad hoc projects. They can also be used to host basic apps such as email.
Companies using the Microsoft Office 365 or Google Apps email and desktop productivity suites are effectively using a public cloud service. They are also popular in the CRM, ERP, HR, social media management, and data storage and data archiving market segments, to name but a few.
Hybrid cloud infrastructures
If organizations are not sure whether to fully choose a private or public cloud solution they can instead go for a hybrid cloud deployment.
A hybrid cloud is an option for companies that have already adopted private clouds or for those not sure about putting too much data or high numbers of apps in the public cloud.
Analyst firm Gartner reckons the hybrid cloud will become a reality in 50 percent of enterprises by 2017.
Hybrid cloud flexibility
As the name suggests, a hybrid cloud comprises both private (internal) and public (external) cloud services. Typically, a business might run an application primarily on a private cloud, but rely on a public cloud to accommodate spikes in usage.
A hybrid cloud delivers additional flexibility and scalability to businesses employing private clouds, but which at times also require additional on-demand scalability, in response to unexpected surges in workload or at recurring times of peak usage.
Customized rules and policies govern areas such as security and the underlying infrastructure, with tasks allocated to internal or external clouds as necessary.
Businesses can house less-sensitive data in a public cloud and more sensitive data in-house, where access control measures - such as authentication, encryption and data confidentiality - can be more easily implemented and controlled for greater security. Such a solution is chosen for some e-commerce operations, for instance.
The work of processing the orders can benefit from the scalable characteristics of public cloud resources, while legal regulations strictly governing how personal and payment information can be handled, dictate that sensitive data stays "on-premise" in a private cloud.
This hybrid solution therefore places the order processing and transactional front-end of the "shop" in the public cloud, while it keeps the payment and account management services protected in a private cloud.
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Désiré has been musing and writing about technology during a career spanning four decades. He dabbled in website builders and web hosting when DHTML and frames were in vogue and started narrating about the impact of technology on society just before the start of the Y2K hysteria at the turn of the last millennium.