Single-Tenant vs. Multi-Tenant Cloud Environments

What is Single-Tenant and Multi-Tenant?

Single-tenant architecture refers to a single instance of the software and any supporting architecture used to support a single customer or tenant. There is no sharing this instance with any other customers or providers. Any additional customers get their instances that are completely isolated from each other. The host may continue to manage this instance, but the customer has the most control over customizing the software and infrastructure. Generally speaking, because fewer users handle the instance, this offers greater confidentiality, security, backup options, and performance compared to more widely shared software. Naturally, this structure costs more.

By contrast, multi-tenant architecture describes a single software instance, and its architecture runs a single application but is shared between multiple customers or tenants simultaneously. Customer data is kept separate, but everything else is shared, including the infrastructure, codebase, and database. Individual users can still freely adjust database schemas and UI effects and change some of the application’s rules. This structure lowers operations costs by leveraging economies of scale compared to single-tenant environments. With proper scaling, this environment can mitigate the limitations of sharing a single instance with multiple users.

There does exist mixed-tenant architecture where components of an application are dedicated to single users while others parts are shared. This does draw on strengths from the main two architectural structures by sharing resources with as many users as possible, but ensuring that data and some functions are kept isolated.

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Strengths and Shortcomings of Single-Tenant Architecture

Having an isolated environment provides much less complexity and data to juggle. Developers will have to worry less about complex scripting and potentially mixing user data during migration. Architecture is inherently similar from instance to instance, making migration easier. Since customers get a dedicated instance, they have free reign to modify their instance without impacting other customers. By confining all their data to a single instance with no shared users, there is less chance of a data breach, and any data breaches that occur will only affect one customer at a time.

Using single-tenant architecture isn’t the most efficient way to structure a cloud application. As more customers are onboarded, developers will need to employ additional instances, making management for smaller teams increasingly difficult. With more machines also comes increasing costs to manage multiple units simultaneously. There is no telling how customers will spend the resources they have, meaning individual instances could go heavily underutilized. Worst case scenario is if the customers use none of the resources provided to them.

Strengths and Shortcomings of Multi-Tenant Architecture

Opposite to single-tenant architecture, multi-tenant instances are far easier to manage. With multiple customers using fewer instances, maintenance will take much less time to conduct and, as such, is common practice for many SaaS platforms. Underutilizing resources is less likely because other customers will more likely use resources that some users aren’t using on the same server. With fewer instances to manage and greater frequency with which those resources are used, this architectural method is significantly more cost-efficient.

Though multi-tenant architecture is better from a customer-friendly perspective, it’s not without shortcomings. By clustering personal data from multiple users on a single server, data breaches can potentially be more catastrophic. There are fewer internal barriers for infiltrators to pass through than if the data was isolated. In terms of cost tracking, tethering resources to multiple users will make tracing extraneous costs more difficult in the long run. These troubles aren’t strong enough to be significant deterrents for this type of system, but these are worth considering.

Which Method is Better?

Though single-tenant is not as cost-efficient as multi-tenant, single-tenant should not be immediately dismissed. Some industries require data protection for compliance requirements, so keeping individual customers isolated is more ideal than keeping costs low. Healthcare and finance handle copious amounts of personal data, and industry regulations like HIPAA mandate patient confidentiality between the customer and the provider. Between companies that need to provide for fewer customers at a time, the difference in operating costs may not be as significant enough to require cost efficiency.

For the bulk of the SaaS industry, maintaining a multi-tenant architectural structure will be the most ideal. Despite the potential vulnerabilities, maintaining cost-efficiency for a high number of customers should be more ideal. Because of the nature of the cloud, maintaining fewer instances can help ease the distribution of maintenance staff, too. This method is generally the more commonly used structure.