Windows Server 2008: DFS Replication
A previous blog post mentioned some of the more end-user visible new features in Windows Server 2008. There is another less visible design enhancement on Windows Server 2008. Let us explore this change and find out how it can be beneficial to Server 2008 based deployments of the DFS Replication service.
Windows Server 2003 R2: On Windows Server 2003 R2, the staging area is contained within a folder under the replicated folder itself. Basically, there is a hidden sub-folder called ‘DfsrPrivate’ under the root of every replicated folder. This hidden folder contains private information stored by the DFS Replication service on a per-replicated folder basis. This private information includes the ‘ConflictAndDeleted’ directory, the ‘PreExisting’ directory and the ‘Staging Area’ for that replicated folder. The ‘PreExisting’ directory doesn’t exist on the Primary member in the replication group. An example of this behavior is illustrated in Figure 1, where the replicated folder ‘Reports’ has its Staging area, Conflicts and Deleted folder and Pre-Existing folder locations stored under the ‘DfsrPrivate’ subfolder. The size of these locations also contributes to the quota usage statistics for the replicated folder.
Windows Server 2008, WS2008, DFS, Replication, Knowledgebase
File replication has changed however as of Windows Server 2003 R2. In particular, there are now two different replication services built into the platform, namely:
DFS Replication. This service is new and can be used not just for replicating DFS trees to provide fault tolerance and better performance, but even simply just replicating files between servers for any purpose. More about this new service in a moment.
File Replication Service (FRS). This is the original replication service, first released with Windows Server 2000, though somewhat enhance. In R2, the FRS is only used for replicating SYSVOL content on domain controllers and nothing else.
What's great is that the new DFS Replication service has a totally revamped replication engine that uses a new replication algorithm called Remote Differential Compression (RDC). This new algorithm replicates only the changes to files and not the files themselves, which means that DFS now works much better over slow WAN links than before. In addition, the new replication engine supports bandwidth throttling and replication scheduling, plus it operates on a multi master replication model. The overall result is that DFS in Windows Server 2003 is much more solid in terms of its reliability and performance than before.