Configuring Central Store

In Windows Server 2008 and Windows Vista, Microsoft replaced the token-based administrative template (ADM) files used with previous versions of Group Policy with an XML-based file format (ADMX).  Administrative templates are the files defining the registry-based settings that appear in GPOs.
Earlier Windows versions created a copy of the ADM files for each GPO administrators created and placed them in the SYSVOL volume of a domain controller. A large Active Directory installation could easily have dozens of GPOs and each copy of the ADM files required 4 MB of storage. The result was a condition called SYSVOL bloat, in which there were hundreds of megabytes of redundant information stored on SYSVOL volumes, which had to be replicated to all the domain controllers for the domain.
To address this problem, Group Policy tools can now access the ADMX files from a Central Store, a single copy of the ADMX files stored on domain controllers. To use a Central Store, you must create the appropriate folder in the SYSVOL volume on a domain controller.
By default, tools such as the Group Policy Management Console (GPMC) save the ADMX files to the %systemroot%PolicyDefinitions folder, which on most computers is C:Windows PolicyDefinitions. To create a Central Store, you must copy the entire PolicyDefinitions folder to the same location as the Group Policy templates; that is, %systemroot%SYSVOL sysvol<domain name>Policies, on a domain controller, or, in universal naming convention (UNC) notation, \< domain name >SYSVOL< domain name >Policies.