multi-tenancy

Importance of multi-tenancy

Multi-tenancy has seen a lot of could adoption and is used most with cloud computing. Multi-tenant architectures are found in both public cloud and private cloud environments, allowing each tenant's data to be separated from each other. For example, in a multi-tenant public cloud, the same servers will be used in a hosted environment to host multiple users. Each user is given a separate and ideally secure space within those servers to store data.

Multi-tenancy is also important for the scalability of public and private clouds, and has helped make multi-tenancy a standard. The multi-tenant architecture can also aid in providing a better ROI for organizations, as well as quickening the pace of maintenance and updates for tenants.

Types of multi-tenant architecture

There are three main multi-tenancy model types, all with varying levels of complexity and costs. A single, shared database schema is a multi-tenancy model with a multi-tenant database. This is the simplest form out of the three and is a relatively low cost for tenants because of the use of shared resources. This form uses a single application and database instance to host tenants and store data. Using a single, shared database schema allows for easier scaling; however, operational costs can be higher.

Another multi-tenant architecture includes the use of a single database with multiple schemas. This tenant system uses a single application instance with individual databases for each tenant. In addition, this architecture has a higher cost with more overhead with each database. It is a valuable architecture when data from different tenants need to be treated differently -- such as if they had to go through different geographic regulations.

The third type of multi-tenant architecture hosts data in multiple databases. This model is relatively complex in terms of management and maintenance, but tenants can be separated by a chosen criterion.

Advantages and disadvantages of multi-tenancy

There are a number of advantages and disadvantages that come with becoming a host provider and a tenant with multi-tenancy. Some advantages include:

• It is less expensive when compared to other tenant hosting architectures.
• An offering of pay-for-what-you-need pricing models.
• Tenants don't have to worry about updates, since they are pushed out by the host provider.
• Tenants don't have to worry about the hardware their data is being hosted on.
• Providers only have to monitor and administrate a single system.
• The architecture is easily scalable.

Some disadvantages, however, that come with multi-tenancy include:

• Multi-tenant apps tend to be less flexible than apps in other tenant architectures, such as single-tenancy.
• Multi-tenancy is, in general, more complex than single-tenancy.
• Multi-tenant apps need stricter authentication and access controls for security.
• Tenants have to worry about noisy neighbors, meaning someone else on the same CPU that consumes a lot of cycles, which may slow response time.
• Downtime may also be an issue depending on the provider.

Examples

In cloud computing, the meaning of multi-tenant architecture has broadened because of new service models that take advantage of virtualization and remote access. A software-as-a-service (SaaS) provider, for example, can run one instance of its application on one instance of a database and provide web access to multiple customers. In such a scenario, each tenant's data is isolated and remains invisible to other tenants. Multi-tenancy can also be implemented in multi-tier systems such as an SAP system.

Multi-tenant vs. single-tenant

Multi-tenancy can be contrasted with single-tenancy, an architecture in which each customer has their own software instance and may be given access to source code. In single-tenant architectures, a tenant will have a singular instance of a SaaS application dedicated to them, unlike multi-tenancy where there are shared services. Because each tenant is in a separate environment, they are not bound in the same way that users of shared infrastructure would be; meaning single-tenant architectures are much more customizable.

Multi-tenancy is the more used option of the two, as most SaaS services operate on multi-tenancy. In comparison to single-tenancy, multi-tenancy is cheaper, has more efficient resource usage, fewer maintenance costs as well as a potential for larger computing capacity. With a multi-tenant architecture, the provider only has to make updates once. With a single-tenant architecture, the provider must touch multiple instances of the software in order to make updates.

A potential customer would likely choose a single-tenant infrastructure over multi-tenancy for the ability to have more control and flexibility in their environment -- typically to address specific requirements.