An overview of cloud approaches
The cloud provider market is currently saturated with a multitude of different private, public, and hybrid cloud solutions, so choice is not a problem for companies looking to implement public, private, or hybrid cloud solutions.
Consequently, choosing a cloud solution can sometimes be quite a daunting task, given the array of different options that are available.
The battle between public and private cloud is still in its infancy, with only around 25 percent of the industry using public cloud, despite its perceived popularity, with solutions such as Amazon Web Services, Microsoft Azure, and Google Cloud taking a large majority of that market share. However, this still means that 75 percent of the cloud market share is available to be captured, so the cloud computing market will likely go through many iterations in the coming years.
So why are many companies considering public cloud in the first place and why does it differ from private and hybrid clouds?
Public clouds
Public clouds are essentially a set of data centers and infrastructure that are made publicly available over the Internet to consumers. Despite its name, it is not magical or fluffy in any way. Amazon Web Services launched their public cloud based on the idea that they could rent out their servers to other companies when they were not using them during busy periods of the year.
Public cloud resources can be accessed via a Graphical User Interface (GUI) or, programmatically, via a set of API endpoints. This allows end users of the public cloud to create infrastructure and networking to host their applications.
Public clouds are used by businesses for various reasons, such as the speed it takes to configure and using public cloud resources is relatively low. Once credit card details have been provided on a public cloud portal, end users have the freedom to create their own infrastructure and networking, which they can run their applications on.
This infrastructure can be elastically scaled up and down as required, all at a cost of course to the credit card.
Public cloud has become very popular as it removes a set of historical impediments associated with shadow IT. Developers are no longer hampered by the restrictions enforced upon them by bureaucratic and slow internal IT processes. Therefore, many businesses are seeing public cloud as a way to skip over these impediments and work in a more agile fashion allowing them to deliver new products to market at a greater frequency.
When a business moves its operations to a public cloud, they are taking the bold step to stop hosting their own data centers and instead use a publicly available public cloud provider, such as Amazon Web Services, Microsoft Azure, IBM BlueMix, Rackspace, or Google Cloud.
The reliance is then put upon the public cloud for uptime and Service Level Agreements (SLA), which can be a huge cultural shift for an established business.
Businesses that have moved to public cloud may find they no longer have a need for a large internal infrastructure team or network team, instead all infrastructure and networking is provided by the third-party public cloud, so it can in some quarters be viewed as giving up on internal IT.
Public cloud has proved a very successful model for many start-ups, given the agility it provides, where start-ups can put out products quickly using software-defined constructs without having to set up their own data center and remain product focused.
However, the Total Cost of Ownership (TCO) to run all of a business's infrastructure in a public cloud is a hotly debated topic, which can be an expensive model if it isn't managed and maintained correctly. The debate over public versus private cloud TCO rages on as some argue that public cloud is a great short-term fix but growing costs over a long period of time mean that it may not be a viable long-term solution compared with private cloud.
Private cloud
Private cloud is really just an extension of the initial benefits introduced by virtualization solutions, such as VMware, Hyper-V, and Citrix Xen, which were the cornerstone of the virtualization market. The private cloud world has moved on from just providing virtual machines, to providing software-defined networking and storage.
With the launch of public clouds, such as Amazon Web Services, private cloud solutions have sought to provide like-for-like capability by putting a software-defined layer on top of their current infrastructure. This infrastructure can be controlled in the same way as the public cloud via a GUI or programmatically using APIs.
Private cloud solutions such as Apache CloudStack and open source solutions such as OpenStack have been created to bridge the gap between the private cloud and the public cloud.
This has allowed vendors the agility of private cloud operations in their own data center by overlaying software-defined constructs on top of their existing hardware and networks.
However, the major benefit of private cloud is that this can be done within the security of a company's own data centers. Not all businesses can use public cloud for compliance, regularity, or performance reasons, so private cloud is still required for some businesses for particular workloads.
Hybrid cloud
Hybrid cloud can often be seen as an amalgamation of multiple clouds. This allows a business to seamlessly run workloads across multiple clouds linked together by a network fabric. The business could select the placement of workloads based on cost or performance metrics.
A hybrid cloud can often be made up of private and public clouds. So, as an example, a business may have a set of web applications that it wishes to scale up for particular busy periods and are better suited to run on public cloud so they are placed there. However, the business also needs a highly regulated, PCI-compliant database, which would be better-suited to being deployed in a private on-premises cloud. So a true hybrid cloud gives a business these kinds of options and flexibility.
Hybrid cloud really works on the premise of using different clouds for different use cases, where each horse (application workload) needs to run a particular course (cloud). So, sometimes, a vendor-provided Platform as a Service (PaaS) layer can be used to place workloads across multiple clouds or alternately different configuration management tools, or container orchestration technologies can be used to orchestrate application workload placement across clouds.
Software-defined
The choice between public, private, or hybrid cloud really depends on the business, so there is no real right or wrong answer. Companies will likely use hybrid cloud models as their culture and processes evolve over the next few years.
If a business is using a public, private, or hybrid cloud, the common theme with all implementations is that they are moving towards a software-defined operational model.
So what does the term software-defined really mean? In simple terms, software-defined means running a software abstraction layer over hardware. This software abstraction layer allows graphical or programmatic control of the hardware. So, constructs, such as infrastructure, storage, and networking, can be software defined to help simplify operations, manageability as infrastructure and networks scale out.
When running private clouds, modifications need to be made to incumbent data centers to make them private cloud ready; sometimes, this is important, so the private data center needs to evolve to meet those needs.
