You may argue the difference between SaaS and the Cloud — about how one is a technology and the other is market-ese — but one factor you cannot argue about anymore is how multitenancy must be the basis for SaaS business software going forward. In September, Oracle CEO Larry Ellison, at their conference Oracle OpenWorld, had the IT world a-buzz about how multitenancy is not secure.

Says Ellison:

“Multitenancy is a horrible idea. What it means is, everyone’s data is commingled, everyone’s customer list is in a single database. That’s a horrible security model. In the 21st century, the way we support multiple customers is called ‘virtualization.’”

Certainly Ellison is entitled to his belief (or his right to say it), but let’s face it: the more copies of Oracle you have running (virtual or otherwise), the better it is for Oracle.

Software companies should consider stackware a “horrible SaaS business model” — especially in that it negates the business, operational, and economic value of multitenancy: everything from streamlining deployment operations, improving core development, maximizing common resources, and only repeating what you need, not the entire frigging architecture.

You might even argue that having multiple databases could be considered even less secure because now you’ve created many entry points into your systems and no way of knowing when you need to lock down the entire platform. One more thing: data in a multitenant environment is not “commingled.” Tenant walls, if built properly, still require you to have access rights to see data — access rights that, as just mentioned, can be shut down from a central point. No one freaks out in an apartment building about their neighbors commingling their groceries or sheets.

At Softletter’s SaaS University last week, the topic of multitenancy was a lot more constructive. Several sessions touched on it from establishing a basic understanding of how it works to what is really on the minds of SaaS businesses. Mike Ormerod from Progress Software had an excellent overview and it refutes Ellison’s point, identifying several types of multitenancy in which you can have multiple apps, multiple databases, even multiple architectures. Likewise, our own platform refutes Ellison’s point about a single database as you can build essentially instances between infrastructures that act like tenants, and deploy across instantiations.

That’s not to say you absolutely need multitenancy. If you’re building B2C type solutions or specific point solutions, not having MT is not a deal breaker. But for enterprise class solutions where a lot of complexity happens at the configuration level and where your clients are demanding manageable customization, not having multitenancy can increase your operating and licensing costs dramatically.