The phrase cloud is used to describe a situation where software and data are accessed over the internet. Because the physical location and who controls the programs and data can vary, and the internet makes access available to a range of devices such as smart phones and tablets, this leads to various hosting options as well as software solutions with degrees of ‘cloud compatibility’.

Hosting:

The options for hosting can be broadly summarised as: 

Pure Cloud – A third party provides all services and achieves optimum pricing by sharing the services across as many customers as possible.

Vendor hosted – A third party provides a tailored and independent set of services to each customer.

Client Hosted – The customer uses a vendor to provide hardware, infrastructure, and connectivity services only. The software and data is conrolled and maintained by the customer.

On premise – The customer provides all services for themselves within their workplace. 

Software:

The options for software can also be broadly summarised into: 

True Cloud – Runs inside web browsers with device sensitive forms. I.e. forms adjust for desk top, tablet, and smart phone displays. Most pure cloud solutions will meet these requirements. 

Browser based – Will function inside a browser but doesn’t adapt well to different display
systems.

Cloud Enabled – Doesn’t function inside a browser, uses VPN and RDP technology to connect over the internet. Typically this requires one or more applications to be installed on the local device to enable access.

Multi-Tenant – For technical reasons, a single instance of a piece of software handling multiple organisations is more efficient than each organisation running their own copy of the same software. However for a single piece of software to handle different organisations at the same time and keep storage and views of the data completely separate, requires that software to be written in a particular manner. Such software is known as ‘Multi-Tenant’ software.

So while all software running on any server that is accessed via the internet is running ‘in the cloud’, if it’s not ‘Multi-Tenant’ then it’s not ‘Pure Cloud’ because it can’t handle multiple organisations at the same time.

Single-Tenant – A situation where a piece of software is handling only one organisation, is known as a ‘Single Tenant’, even if the software is ‘Multi-Tenant’ capable. The reason why an organisation might want to use ‘Multi-Tenant’ capable software in ‘Single Tenant’ mode is so it can be customised, including integrations, without impacting other organisations, and other organisations workloads will not impact performance.

Also, because the need for multi-tenant capability has only become common recently, much of the multi-tenant software is not as robust, or at times as feature rich as older single-tenant solutions. 

So to summarise, a Multi-Tenant, Pure Cloud solution can be the simple low cost option, while the reasons for preferring a  Single Tenant Cloud solution could include performance, and product maturity in terms of reliability and features.