Polling properties
Applies To: Windows Server 2003 R2
When this option is available: Available when the DFS Management snap-in connects to a namespace server that is running a version of Windows Server 2003 R2 or Windows Server 2003 with Service Pack 1 (SP1).
Supported namespace types: Domain-based only.
Where configured: Namespace properties, Advanced tab.
To maintain a consistent domain-based namespace across namespace servers, it is necessary for namespace servers to periodically poll Active Directory to obtain the most current namespace data.
You can optimize how this polling occurs by choosing one of the following options:
Optimize for consistency
Supported namespace server operating systems: Windows Server 2003 and Windows 2000 Server.
In this mode, which is enabled by default, the Distributed File System service attempts to keep the domain-based namespace highly consistent on all namespace servers. This consistency is achieved as follows:
Namespace servers running Windows Server 2003 and Windows 2000 Server poll the primary domain controller (PDC) emulator every hour by default.
Namespace servers running Windows Server 2003 poll the PDC emulator after the namespace changes to obtain the updated namespace data without needing to wait for Active Directory replication to replicate the updated namespace object to all domain controllers. However, this process can cause an increased load on the PDC emulator in namespaces that have more than 16 namespace servers and in namespaces that change frequently.
This mode is recommended only for domain-based namespaces that are hosted by fewer than 16 namespace servers. For namespaces hosted by more than 16 namespace servers, we recommend choosing the Optimize for scalability option.
Optimize for scalability
Supported namespace server operating systems: Windows Server 2003.
This mode, also known as root scalability mode, allows organizations to use more than the recommended 16 namespace servers for hosting a domain-based namespace in consistency mode. When root scalability mode is enabled, namespace servers do not send change notification messages to other namespaces servers when the namespace changes, nor do they poll the PDC emulator every hour. Instead, they poll their closest domain controller every hour to discover updates to the namespace.
Root scalability mode reduces network traffic to the PDC emulator at the expense of faster updates to all namespaces servers. Updates are still made to the namespace object in Active Directory on the PDC emulator, but namespace servers do not discover those changes until the updated namespace object replicates (using Active Directory replication) to the closest domain controller for each namespace server. After root scalability mode is enabled, clients might have an inconsistent view of the namespace until the most up-to-date version of the namespace object is replicated to all domain controllers and the namespaces servers poll a domain controller to discover the changes.
Note
Namespace servers running Windows 2000 Server continue to poll the PDC emulator every hour by default, even if this option is selected.
To change the polling method, see Optimize namespace polling.