When to separate systems into multiple Dynamics CRM instances

Question

My organization is just starting to dive into Dynamics CRM and one of the questions that has come up is when should we combine various applications into one instance and when should they be separated into multiple instances?

I know the answer to that question depends on the situation, so I'm trying to come up with a list of questions that can be asked to help determine which direction makes the most sense.

I'm having a surprisingly difficult time finding any discussion of this online, so thought I'd ask here. So, what questions do you ask when deciding whether a system/set of functionality should be in a separate instance?

Edit: I wasn't very clear about our type of organization. I work for a City with several Departments that provide different services and serve different customers with often very different functionality required.

I'm concerned about the urge to put all of these different systems that have different functionality and track different "customers" into one system. I fear there will be issues about managing all of the various entities that apply to different systems and ensuring that requests for changes from one set of users doesn't cause problems for a different set of users.

I'm sure sometimes it will make sense to combine multiple systems into one instance, but I think there may be just as many times where we don't want to put them together, so I wanted to come up with a list of questions to ask.

Some basic ones would be: 1) Do systems share common data (e.g., same customers)? 2) Do systems share common functionality? 3) Do systems collect the same kind of data? 4) Are there requirements to report on combined data from these systems? 5) Will it be easier to manage security by separating instances or through user roles?

Answer 1

In my experience a single instance is the norm. The benefits of a single instance are very significant in my opinion.

A few points you may want to consider:

• Do you want data in silos? If so, multi-instance provides a very easy way to achieve this. However a single instance with appropriate security modelling can also achieve this.
• Do you want to combine data across applications into a single business process? If so, multi-instance means you have to build an integration between instances. Single instance does not have this problem.
• Do you want to use custom built features in every instance? If so, a single instance provides this straight away. Multi-instance requires separate development and deployment to every instance which may increase costs.
• Have you considered licensing? I'm not a licensing expert, but I believe if you are online multi-instance will attract a higher license cost.

As a rule of thumb I would say a single instance is the default position, as it allows you to easily combine data and processes. If you want to go multi-instance just have a good reason why and be sure its not something that can be provided by a single instance.