For businesses researching Cloud migration options, the battle between choosing to use either a Public or Private Clouds is a never-ending one. 

For some, the idea of transferring workloads to the Cloud can be confusing and a little ‘foggy’, especially when Cloud Computing vendors categorise offerings under different Cloud related or ‘-as-a-Service’ categories. This blog aims to identify some of the main differences between the two ‘Public’ and ‘Private’ technologies.

Private clouds vs public clouds

Private, Public and Hybrid Clouds.

In order to fully explore the relationship between Private and Public Clouds, it is necessary to start by defining the concepts. If you would like a full list of other Cloud service definitions then please visit the virtualDCS ‘Cloudopedia’ glossary.

What is a Private Cloud?

A Private Cloud traditionally describes a virtual infrastructure that has been constructed for the sole use of one business, which can either be hosted and maintained off-site by the Cloud provider, or maintained by the business on-site.

What is a Public Cloud?

In its simplest form, a Public Cloud is defined as an infrastructure which is shared between organisations. The platform is monitored and maintained off-site by the provider, as they will also be maintaining the platform for other customers using the resources.

So, which would be most relevant to your business?

Total cost of ownership

The overall total cost of ownership is higher with a Private Cloud than a Public one, as the business would have to directly purchase the hardware, as opposed to renting it from the provider. This large acquisition could potentially hinder cash flow.

On the other hand, owning a Private Cloud can be beneficial for businesses that require a dedicated Cloud resource and some providers may offer to buy the Private Cloud hardware for the customer and include the fee for it in the monthly or quarterly service charge.

Flexibility

Theoretically, your business could never outgrow a Public Cloud, as the vendor will ensure that the shared platform has enough room for customers to expand and increase their resources. However, with a Private Cloud this is another matter entirely and new hardware would have to be purchased, or data deleted, if the business was close to capacity.

Security

Private Clouds offer complete physical isolation from other companies, which for some businesses could be necessary under legal legislation if confidential data is being held. If the business decides to opt for a Public Cloud then the effectiveness of the virtualisation software on the platform must be assessed accordingly, as different technologies offer different security levels. For example, a ‘VMware virtual server’ offers the complete separation of all files, where some containerised “Virtual Server” options can share some common system files with the host server, such as Parallels’ Virtuozzo.

The location in which the platform is housed could also cause security concerns. If the server for the Private Cloud is stored on the business’ premises, it can be assumed that the building would be a less secure location than a Data Centre, where a Public Cloud would traditionally be stored. This issue could however be rectified through physical co-location.

Innovation

Public clouds are typically built by large organisations who can offer new functionality across the platform as they wish – for example, adding options for Load Balancing is made much easier (and potentially cheaper) than with Private Clouds.

Billing

Public Cloud providers offer flexibility of billing, usually pay-as-you-go, with monthly contracts. By contrast, Private Cloud contracts can run for years and offer a guaranteed fee, regardless of the amount of work done by the Cloud. Public Clouds are an attractive option for developers, where the workload is typically lightweight, transient and potentially targeted at the cheapest available Public Cloud space.

Experience and maintenance

What level of technical experience does your internal I.T. department have? Would individuals need training in order to maintain a Private Cloud? Would it be more cost effective and efficient for your company to ask the Cloud provider to maintain the Private Cloud for you? Alternatively, a Public Cloud would be maintained by the provider.  There is also the option of Managed Services, allowing companies to run a Private Cloud without the need to have the skills in-house.

It is also important to acknowledge the fact that Cloud Computing is currently at the forefront of technological innovation and is attracting some of the strongest industry leaders. A dedicated provider would have in-depth virtualisation experience which many average I.T. departments would not be able to compete with.

To summarise, Cloud Computing provides a number of advantages for businesses as a whole and the decision between the two Cloud concepts is reliant on these and the level of control that the business wishes to have over its I.T. facilities. There is, however, a third option available for consideration… a Hybrid Cloud.

What is a Hybrid Cloud?

A Hybrid Cloud is a mixture of the two concepts above, some workloads are run from dedicated, private hardware, and other workloads are hosted on shared infrastructure. For example, the customer may want to host its email server in a private cloud, offering a fixed fee and a guaranteed level of availability/performance, yet require that their web servers are hosted on hardware managed by the Public Cloud provider. Hybrid Clouds are becoming increasingly common within the industry as internal I.T. departments merge skills with external service providers.

For more information on Cloud Hosting solutions feel free to contact a member of the virtualDCS team, or to browse any of our related guides.

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