In Part One we defined and described three different kinds of software as a service cloud deployments – Single-Tenant SaaS, Multi-Tenant SaaS, and Hybrid SaaS. But what are the advantages and disadvantages of each?
With Single-Tenant SaaS, the main advantage is that you retain the most granular control of your implementation. The main advantages are as follows:
- Normally you retain control of the upgrade process, meaning no surprises or disruption to your business operations.
- It is possible for you to build and maintain custom coding specific to your implementation.
- You have complete control over your data, as it is maintained on a single server dedicated to you.
The disadvantages are primarily that it is more work to have to think about, and possibly perform the upgrades yourself. Custom coding also requires maintenance, and may break with a software upgrade. Single-Tenant SaaS is typically written on older, legacy code that is ported to web applications, and may not be as efficient as new code bases.
Multi-Tenant SaaS is where we see the bulk of new enterprise software development taking place. It’s primary advantage is convenience.
- It scales very easily, as you are sharing your implementation with many others spread out over multiple servers.
- The maintenance and support is provided by the vendor; very few internal IT resources are needed.
- Upgrades are automatic and normally invisible to the client.
Although this is the direction that many vendors are going, it is not all roses with Multi-Tenant SaaS. Your data co-mingles with other clients, and is only separated by system permissions. You have no control and few change management options, as the updates are published and they are not optional. Since you are sharing the implementation with others, code customizations are not permitted; you will have less latitude in your business process/operational decisions.
As we’ve defined it here, Hybrid is typically somewhere in the middle of the two above models. We normally see this where a vendor is slowly moving between a traditional on-premise product and a multi-tenant web product, and not all modules have been written in the newer code yet. There are no real advantages to the model, as it is transitional in nature.