Should you care if your cloud application is multi-tenant?


By David Terrar, CEO of D2C Limited, Co-founder of Cloud Advocates

When I first came in to the Software as a Service world 10 years back I was a bit of stickler for differentiating properly architected "pure cloud" solutions from old style, client/server, on premise applications that are simply hosted somewhere and available through the Internet.

These days I'm much less concerned over the technicalities. If the business solution you've chosen offers anytime, anywhere access, does the job at a good monthly subscription fee, and performs well, does it really matter? Recently some debate between Marc Benioff of Salesforce warning us to "beware of the false cloud" and Oracle's recent announcement of their Public Cloud has sparked some debate and discussion amongst cloud bloggers and analysts and my "Enterprise Irregular" friends.

The key issue under discussion was multi-tenancy. A single tenant application is where there is one instance (or partition) of the application software and database for each customer. This is easy to do with today's virtualised hardware environments and can be the short route to getting an existing application in to the cloud, essentially just using cloud infrastructure. As a by-product one customer is segregated from another and so it might appear more secure.

Multi-tenant solutions share software and database amongst all customers in a public cloud service, and the software itself handles the secure separation of customer's data. Dennis Howlett summarizes the discussion on Zdnet and input from the likes of Bob Warfield, and Phil Wainewright chimes in with his pro multi-tenant position.

Part of the argument is that Total Cost of Ownership is the key, and that multi-tenant really only matters to the vendor's cost structure. The vendor can share resources more easily across their community of customers - paying for one copy of operating software and database across all customers rather than many, using less hardware resources as you haven't got the overhead of multiple instances or a virtual machine per customer - that kind of thing. As Phil and Dennis point out, that's only part of the story. Dennis talks about SAP's Business ByDesign product which started a few years back as single tenant, didn't get very far, but has now been re-architected to be multi-tenant and is starting to take off.

A multi-tenant approach has some key advantages and the vendor has a different mindset, geared towards enhancing the application for the good of the community of customers, as opposed to servicing individual customers. Application maintenance is more straightforward as the vendor is managing one set of code rather than applying updates (or not) to many separate customers. Multi-tenant is geared towards innovation with many/regular software updates and an emphasis on ideas from the customer community.

I always explain that as a vendor of old style, on-premise applications I would demo to customers who told me how they wanted to use the system. After implementation I wouldn't get to see how they actually use the system in practice, which might be very different. With Software as a Service the vendor is running the application for the customer day in day out. They see how the application is actually used in anger. They can watch for bottlenecks and get direct feedback from customers and feed any issues straight back in to the product roadmap. As Phil continues:

"This is before we even start to think about the potential for using pooled aggregate data for benchmarking, validation or trend analysis, along the lines that Dennis Howlett discussed. Most of the benefits of public cloud multi-tenancy have not even begun to be explored, much as the huge transformative impact of the internal combustion engine was unimagined at the beginning of the twentieth century."

Phil's right. TCO is important, but you should be looking for business applications which have innovation as part of their DNA and which will evolve as your business grows. You are more likely to get that with multi-tenant cloud applications.

David Terrar is a consultant and software developer who specialises in the use of Cloud applications and social media in business. He is a co founder of Cloud Advocates, an association of consultants who aim to demystify the Cloud and provide pragmatic help and advice for businesses, organizations and accounting practices. To find out more, visit

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