Cloud computing has very quickly morphed from a good idea to having a utility feel about it. It has suddenly dominated the Internet to the point where there are very few people who use the Internet and have not been touched by it. Why has it become so popular so quickly?
Basically, cloud computing offers costs savings - a 'virtualized' data center is significantly more cost effective than the data centers that supported more traditional IT services. Cloud computing outperforms traditional data centers, in terms of scalability, and, although you might not believe it from the industry press, elements of security.
Alongside a vast array of terms and acronyms that are used to express certain aspects of the cloud computing (BOYD, IaaS, SaaS, etc.) two terms stand out: Public Cloud and Private Cloud.
What is a Public Cloud?
A 'public cloud' is an Internet solution where a service provider makes the resources associated with data centers (RAM, storage, etc.) available to members of the public. Depending on the services provided, this can be done free of charge or for a fee - Gmail's standard email service might represent a free 'public cloud' solution. When a public cloud is offered on a cost basis, it is traditionally offered on a pay-per-usage basis.
What is a Private Cloud?
A 'private cloud' is not available to the general public. It is a platform established usually for a business or an organization. The platform is entirely under the control of the business or organization it was established for, and it is protected by a firewall so that only those permitted to use it can.
What are the key differences between Public and Private Clouds?
Public clouds offer services that a business or organization purchases from a provider. These could be software that a business requires to function (at the office level, this could be typified by Office 356). Storage and processing power are the responsibility of the provider, who often manage their own data centers to do this, or themselves rent capacity from cloud infrastructure providers.
Whereas once businesses and organizations managed their own IT departments and even data centers, now they more often utilize private clouds. Private clouds mimic the functions and capability of IT departments, but rather than owning hardware and software, the functions are virtualized.
Which is best?
Both have public and private clouds have advantages and disadvantages, and which you would use depends on your needs and the resources you have available. The management of a public cloud is almost entirely the responsibility of the provider who established it, while private clouds require in house resources to run them (i.e. IT staff). There is also an initial expense required to set up a private cloud, that is passed on to the business or organization, and this can be quite substantial. The business or organization may also need hardware and software to manage the solution - again a cost that has to be incurred. Public clouds do not usually have substantial set up costs. Generally costs are covered by the provider, and its security is also the provider's responsibility.
Whereas private clouds often incur costs to increase capacity, public clouds are far more scalable. When business/organization activity spikes and additional resources are required to facilitate increased resource usage, these resources are available, and paid for as they are used. This allows a business or organization to focus on its core competencies, and not have business plans limited to available IT capability. As a result, public clouds can support a business or organization's growth better than private clouds.
When businesses or organizations adopt private clouds, they have access to the servers that make up their cloud. This means that it is possible to make them very secure indeed. Public clouds do not allow access to servers, only to resources. As a result, how secure they are is dependent on the capabilities of the provider. Should one person's credentials be made available to another individual, that individual potentially has access to all of the data stored in a public cloud. Private clouds outperform public clouds in terms of security benefits. Your business or organization's data is behind a firewall and thus more secure. In addition, it can be physically more secure. In times of difficultly, or where there are potential threats, a private cloud can be completely divorced from the Internet until danger passes.
With a private cloud, a business or organization knows exactly where data is stored. This is a major advantage because in many countries there are legal restrictions that require data related to a country's citizens to be stored within that country's border. Public clouds by their nature mean that data can be stored anywhere. Microsoft is currently fighting efforts by US government agencies to release data about US citizens. The data is actually held on servers in Ireland.
With a private cloud, a business or organization can secure its infrastructure from natural disaster, but with a public cloud, your are dependent on your provider taking these precautions. In the worst case scenario, if a public host goes out of business, everything is lost. But with a private cloud, the platform remains intact, even if the provider does not.
Beyond this though, private clouds can be directly and physically accessed by malicious individuals working for your business or organization, and as a result, they could potentially put your entire infrastructure at risk. In a public cloud, sophisticated sets of procedures and protocols can be put in place to ensure that only people who need access to data get access to it. Of course, as we have said, there is no physical access to public cloud servers.
In addition, if for example your infrastructure is hacked or is attacked in any fashion (DoS, etc.), you need the capability to deal with it - public clouds have support teams that are available 24/7 to ensure platform integrity. Likewise, if the electricity goes off, you need something to support you - a backup generator, etc. In a public cloud data is simply transferred to another machine in another location.
As you can see, private clouds are more available to people who can manage them - and that usually means bigger businesses or organizations. Public clouds can be accessible to a single individual. To determine exactly which cloud you need, a careful audit needs to be conducted to assess your business or organization's requirements and the in house capability available to support each type of cloud.