Microsoft KB Archive/220938

= Description of the FRS Replication Protocol, Notification and Schedule for DFS Content =

Article ID: 220938

Article Last Modified on 2/26/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Datacenter Server

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This article was previously published under Q220938



SUMMARY
The File Replication Service (FRS) is a multi-threaded, multi-master replication engine that replaces the LMREPL (LAN Manager Replication) service in previous versions of Microsoft Windows NT. Windows 2000 domain controllers and servers use FRS to replicate system policies and login scripts for Windows 2000 and down-level clients.

Optionally, FRS can replicate content between Windows 2000 servers hosting the same fault-tolerant Distributed File System (DFS) roots or child-node replicas.

This article discusses the replication protocol, notification, and schedule used by FRS for replicating DFS content.

For additional information about FRS and DFS support on a Windows 2000 Server Cluster (MSCS), click the article number below to view the article in the Microsoft Knowledge Base:

235529 Kerberos support on Windows 2000 Server Clusters



Replication Protocol
FRS uses Remote Procedure Call (RPC) over Transmission Control Protocol (TCP) for inter-site and intra-site replication for DFS content. While well suited to moving files, Simple Mail Transfer Protocol (SMTP) or mail-based replication (MBR) is limited to replication of the schema, configuration, and global catalog naming contexts in the first release of Windows 2000.

Unlike Active Directory replication, FRS-replicated content between sites is not compressed.

Enabling DFS Replication
DFS replication is not enabled by default. To enable, disable or view the DFS replication settings, follow these steps:


 * 1) Start the Distributed File System Manager (DFSGUI.MSC) snap-in.
 * 2) In the left pane, right-click the level of the DFS tree "backed" by more than one Windows 2000 computer, and then click Replication Topology.
 * 3) Click the Enable and Disable buttons as required.

Enabling or disabling replication creates corresponding connection objects in the Active Directory to facilitate the replication of DFS content between partners. The topology for DFS replication is determined by the Distributed File System Manager and its own topology, schedule, and connection objects are separate and apart from the Active Directory.

Replication Notification and Schedule
The FRS service begins the replication process when the NTFS file system change log detects that a file in a DFS-held tree is closed. Changes are held in a 3-second aging cache so that only the last iteration of a file undergoing rapid updates is replicated. This replication latency is analogous to the "Replicator notify pause after modify" registry entry for Active Directory replication. File and folder filters are applied to prevent replication of unwanted files. Replication of small files between servers with low CPU and disk utilization occurs within seconds.

Similar to the Windows 2000 Active Directory directory service, replication in the same site occurs when upstream partners notify downstream partners of pending changes. Downstream partners pull files and folders that have changed since replication last took place, sending acknowledgement to the upstream partner with the receipt of each change.

Replication of DFS content between sites is scheduled using the "Active Directory Users and Computers" (DSA.MSC) snap-in. Downstream partners pull changes according to the replication frequency and the hours replication is enabled. To view DFS connection objects, follow these steps:


 * 1) Start the Active Directory Users and Computers (DSA.MSC) snap-in.
 * 2) On the View menu, click Advanced Features.
 * 3) In the left pane, double-click System, double-click File Replication Service, double-click DFS Volumes and then double-click DFS Root container. DFS connection objects are displayed in the right pane for each level of the DFS namespace where DFS replication is enabled in the Distributed File System Manager (DFSGUI.MSC) snap-in.
 * 4) Right-click the connection object, and then click Change Schedule.

Viewing DFS connection objects in the DS
The Globally Unique Identifiers (GUIDs) for DFS connection objects belong to the NTDS-Connection object class. Connection objects can viewed directly in the DS by using the ADSVW.MSC snap-in or an equivalent program such as LDP.EXE.

For a domain controller in the "A.COM" domain hosting a fault-tolerant DFS root namespace "DFSFT" and a child-node replica "TOOLS," the path in the DS is

CN={59ec0127-ccdf-11d2-8fd1-00c04f8f4f54},CN={d42a1614-cd9e-11d2-8fd2-00c04f8f4f54},CN=DFSFT\TOOLS,CN=DFSFT,CN=DFS Volumes,CN=File Replication Service,CN=System,DC=A,DC=COM

where (reading selected entries from end to beginning):

DC=A,DC=COM is the the A.COM domain

CN=DFSFT is the root of the DFS namespace

CN=DFSFT\TOOLS is the DFS Root name and TOOLS is a DFS child node.

CN={d42a1614-cd9e-11d2-8fd2-00c04f8f4f54}is the GUID for the NTFRS member

CN={59ec0127-ccdf-11d2-8fd1-00c04f8f4f54}is the GUID for the nTDSConnection

Additional query words: FRS NTFRS

Keywords: kbinfo KB220938

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