For each organization, Microsoft Dynamics CRM stores all customer relationship management data in a SQL Server database. Make sure that the computer on which SQL Server is running that maintains the Microsoft Dynamics CRM databases is located near the Microsoft Dynamics CRM Server 2011. This means there should be a high-speed, permanent network connection between the Microsoft Dynamics CRM Server 2011 and the computer that is running SQL Server. A network communications failure between these computers can result in data loss and service becoming unavailable.
SQL Server and Active Directory domain controller placement
The same is true for Active Directory directory service because Microsoft Dynamics CRM depends on it for security information. If communication with Active Directory is lost, Microsoft Dynamics CRM will not function correctly. If communication with Active Directory is inefficient, Microsoft Dynamics CRM performance will be affected. Therefore, it is important to put an Active Directory domain controller on the same high-speed, permanent network connection as the Microsoft Dynamics CRM and SQL Server computers.