The Microsoft CRM 3.0 setup does create four groups in Active Directory to store information about the users and computers included in a Microsoft CRM instance. These groups are called:
They are used to grant access to various system resources to users and do not control access to application functionality directly the way that security roles do. By default, the Microsoft CRM setup creates these groups in Active Directory and hard-codes their names as listed above. You may choose to use a second set of Active Directory groups for your second Microsoft CRM instance in order to eliminate any concurrency issues between the two instances. You can do that by running the Microsoft CRM setup from the command line and specifying an XML configuration file for the configuration. This XML configuration file allows you to specify different names for the aforementioned Active Directory groups. For more information on installing Microsoft CRM using an XML configuration file, refer to Chapter 19 in the Microsoft CRM 3.0 Implementation Guide.
Although you can install two instances of Microsoft CRM 3.0 on the same domain, each instance will require its own hardware. If you need to have two separate instances of Microsoft CRM, it may be a better use of your resources to upgrade to Microsoft CRM 4.0, which supports multi-tenancy and allows you to install two instances of Microsoft CRM on the same hardware. This approach will not only limit your hardware investment, but will also simplify maintenance and provide access to some of the great new functionality available in Microsoft CRM 4.0.
This was first published in December 2008