Experts have long debated the merits and drawbacks between multi-tenant and single-tenant SaaS architectures.
Multi-tenant vendors tout and promote their model, saying it offers efficiencies in terms of IT management, cost cutting, and scale. Single-tenancy vendors claim that only when each client operates within their own independent database, can performance, security, flexibility and integration really be maximised.
Richard Vester, group executive: cloud services at EOH, says it is important to define what these two architectures really mean. “Multi-tenant SaaS architectures are where numerous businesses share the same instance to store their data. In these cases, the instance is usually partitioned to prevent the organisations from accessing each other’s data.
“Single-tenant, also called hosted architectures, happen when each business has its own instance of the software application and the associated infrastructure.”
So which is the better option? “This will depend not only on who you ask, but on the organisation’s business objectives and requirements. Bear in mind that the majority of organisations who begin a SaaS journey do so to try and lessen the burden of IT management and maintenance associated with software investments,” Vester says.
Multi-tenant SaaS comes with cost saving benefits. When resources are pooled, there are significant savings to be realised both in physical hardware, and in energy.
In addition, with multi-tenancy, upgrades become seamless, as no level of customer intervention is needed and multiple customers are upgraded at once. “Moreover, in terms of backups and redundancy, creating that level of redundancy would be a far more technically difficult if thousands and thousands of customers had unique virtual servers.”
Multi-tenancy is not without its challenges, he says. “For one, less customisation is possible. Because numerous tenants run their businesses from the same code and from the same database, individual organisations are not able to tweak and tailor the software to suit their unique needs. Bear in mind that any custom code can impact other clients. The ability to customise is vital to many organisations, but only that company can decide how much. However the chances are that multi-tenant providers have not tailored their offering to your specific needs.”
According to Vester, there is also the issue of changes to the software application being made and deployed to your company without any authorisation, as your business relies on the same code base as all the other tenants. “In the same way, future features and functionality might be delayed or even taken off the product road map as multi-tenant providers will usually focus their efforts on the demands of their larger clients.”
He says there are also many benefits of a single-tenant architecture. “The first that comes to mind, is far better security and privacy. When there is only one instance for each user, the risk of another business accessing your proprietary data, either accidentally or through sabotage, is greatly lowered. In addition, one tenant cannot impact on another tenant’s tasks, which is why they are popular with larger enterprises.”
On the flip side, he says if an organisation opts to run its cloud on-premise, it must bear the full costs of the entire system. “A single-tenant system is usually more costly than its multi-tenant counterpart, and is not always the most efficient use of resources, unless it is fully loaded. For each instance, the underlying software, for example the OS, must be updated.”
Ultimately, both of these architectures provide massive benefits to the organisations who adopt them. “Businesses need to understand what their needs are, and where they are willing to trade off. Customisation? Security? Cost? Each business will know what truly matters to them.”