Microsoft dfs explained

Replication groups, replicated folders, and members are illustrated in the following figure. This figure shows that a replication group is a set of servers, known as members, which participate in the replication of one or more replicated folders.

A replicated folder is a folder that stays synchronized on each member. In the figure, there are two replicated folders: Projects and Proposals. As the data changes in each replicated folder, the changes are replicated across connections between the members of the replication group. The connections between all members form the replication topology. Creating multiple replicated folders in a single replication group simplifies the process of deploying replicated folders because the topology, schedule, and bandwidth throttling for the replication group are applied to each replicated folder.

To deploy additional replicated folders, you can use Dfsradmin. Each replicated folder has unique settings, such as file and subfolder filters, so that you can filter out different files and subfolders for each replicated folder.

Files are tracked using a unique ID, so renaming a file and moving the file within the replica has no effect on the ability of DFS Replication to replicate a file. Cross-file RDC uses a heuristic to determine files that are similar to the file that needs to be replicated, and uses blocks of the similar files that are identical to the replicating file to minimize the amount of data transferred over the WAN. Cross-file RDC can use blocks of up to five similar files in this process.

If you need to change the path of a replicated folder, you must delete it in DFS Management and add it back as a new replicated folder. DFS Replication then uses Remote Differential Compression RDC to perform a synchronization that determines whether the data is the same on the sending and receiving members. It does not replicate all the data in the folder again. Changes to these attribute values trigger replication of the attributes.

The contents of the file are not replicated unless the contents change as well. The following attribute values are replicated by DFS Replication, but they do not trigger replication. The following file attribute values also trigger replication, although they cannot be set by using the SetFileAttributes function use the GetFileAttributes function to view the attribute values. However, the reparse tag and reparse data buffers are not replicated to other servers because the reparse point only works on the local system.

You can choose a topology when you create a replication group. Or you can select No topology and manually configure connections after the replication group has been created. DFS Replication supports copying files to a replication group member before the initial replication. This "prestaging" can dramatically reduce the amount of data replicated during the initial replication.

The initial replication does not need to replicate contents when files differ only by real attributes or time stamps. A real attribute is an attribute that can be set by the Win32 function SetFileAttributes.

If two files differ by other attributes, such as compression, then the contents of the file are replicated. To prestage a replication group member, copy the files to the appropriate folder on the destination server s , create the replication group, and then choose a primary member.

Choose the member that has the most up-to-date files that you want to replicate because the primary member's content is considered "authoritative. For more information about the initial replication, see Create a Replication Group. Journal wraps: DFS Replication recovers from journal wraps on the fly. Each existing file or folder will be marked as journalWrap and verified against the file system before replication is enabled again.

During the recovery, this volume is not available for replication in either direction. For example, creating multiple folders simultaneously with identical names on different servers replicated using FRS causes FRS to rename the older folder s. If an application opens a file and creates a file lock on it preventing it from being used by other applications while it is open , DFS Replication will not replicate the file until it is closed. If the application opens the file with read-share access, the file can still be replicated.

Microsoft does not support creating NTFS hard links to or from files in a replicated folder — doing so can cause replication issues with the affected files.

Hard link files are ignored by DFS Replication and are not replicated. Junction points also are not replicated, and DFS Replication logs event for each junction point it encounters. For more information, see the Ask the Directory Services Team blog. The reparse tag and reparse data buffers are not replicated to other servers because the reparse point only works on the local system. As such, DFS Replication can replicate folders on volumes that use Data Deduplication in Windows Server , or Single Instance Storage SIS , however, data deduplication information is maintained separately by each server on which the role service is enabled.

No, DFS Replication does not replicate files for which the only change is a change to the timestamp. Additionally, the changed timestamp is not replicated to other members of the replication group unless other changes are made to the file.

DFS Replication replicates permission changes for files and folders. Changing ACLs on a large number of files can have an impact on replication performance. However, when using RDC, the amount of data transferred is proportionate to the size of the ACLs, not the size of the entire file. The amount of disk traffic is still proportional to the size of the files because the files must be read to and from the staging folder.

DFS Replication does not merge files when there is a conflict. This ensures that the RPC communication across the Internet is always encrypted. RPC Technical Reference. About Remote Differential Compression. Authentication-Level Constants. There is one update manager per replicated folder. Update managers work independently of one another. By default, a maximum of 16 four in Windows Server R2 concurrent downloads are shared among all connections and replication groups. Because connections and replication group updates are not serialized, there is no specific order in which updates are received.

If two schedules are opened, updates are generally received and installed from both connections at the same time. If the schedule is open, DFS Replication will replicate changes as it notices them. There is no way to configure a quiet time for files. If you are using Windows Server or Windows Server R2, you can create a read-only replicated folder that replicates content through a one-way connection. Doing so can cause numerous problems including health-check topology errors, staging issues, and problems with the DFS Replication database.

If you are using Windows Server or Windows Server R2, you can simulate a one-way connection by performing the following actions:. Train administrators to make changes only on the server s that you want to designate as primary servers. Then let the changes replicate to the destination servers.

Configure the share permissions on the destination servers so that end users do not have Write permissions. If no changes are allowed on the branch servers, then there is nothing to replicate back, simulating a one-way connection and keeping WAN utilization low.

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Privacy policy. DFS Namespaces is a role service in Windows Server that enables you to group shared folders located on different servers into one or more logically structured namespaces. This makes it possible to give users a virtual view of shared folders, where a single path leads to files located on multiple servers, as shown in the following figure:. This topic discusses how to install DFS, what's new, and where to find evaluation and deployment information.

A namespace server is a domain controller or member server that hosts a namespace. The Distributed File System DFS functions provide the ability to logically group shares on multiple servers and to transparently link shares into a single hierarchical namespace.

DFS organizes shared resources on a network in a treelike structure. DFS supports stand-alone DFS namespaces, those with one host server, and domain-based namespaces that have multiple host servers and high availability. Each DFS tree structure has one or more root targets. The root target is a host server that runs the DFS service. Each DFS link points to one or more shared folders on the network.