These scenarios are supported by the Distributed File System (DFS) solution, which includes new tools for DFS Namespaces, a new replication engine known as DFS Replication, and enhanced print management tools.
The Distributed File System (DFS) solution in Windows Server 2003 R2 provides simplified, fault-tolerant access to files and WAN-friendly replication. Distributed File System consists of two technologies:
DFS Replication, the successor to File Replication service (FRS), is a new state-based, multimaster replication engine that supports scheduling and bandwidth throttling. DFS Replication uses a new compression algorithm known as Remote Differential Compression (RDC). RDC is a differential over-the-wire protocol that can be used to efficiently update files over a limited-bandwidth network. RDC detects insertions, removals, and rearrangements of data in files, enabling DFS Replication to replicate only the deltas (changes) when files are updated.
Remote Differential Compression
RDC is an advanced WAN-compatible compression technology that optimizes data transfers over limited-bandwidth networks. Instead of transferring similar or redundant data repeatedly, RDC accurately identifies file “deltas” and transmits only the differences to achieve bandwidth savings. This means, for example, the “deltas” caused by a simple title change in a 3 megabyte (MB) PowerPoint® presentation would take less than one second to replicate over a WAN, in contrast to one minute or more for the entire file.
RDC can also copy any roughly similar file from any client or server to another using data that is common to both computers. This effectively reduces the size of the data sent and the overall bandwidth requirements for the transfer. Local differencing techniques — sometimes called “patching” — compute the differences between two local files, detecting insertions, removals, and rearrangements of data. The differences can then be used to transform the old version to a new version. The differences between two known versions of a file are calculated on a server, and then sent to the client.
Microsoft’s internal RDC performance testing suggests that in some cases, bandwidth reduction factors may reach as high as 400:1.
Automatic recovery from database loss or corruption.
Scheduling and bandwidth throttling for replication schemes.
Multiple replication topologies.
Distributed File System Namespace
DFS Namespaces allow administrators to group shared folders located on different servers and present them to users as a virtual tree of folders known as a namespace. A namespace provides numerous benefits, including increased availability of data, load sharing, and simplified data migration. Users can navigate these virtual namespaces without having to keep track of the names of the physical servers or shared folders hosting the data.
Figure 1: Distributed File System
If local servers become unavailable, DFS Namespace configurations provide for client failover by closest site selection and failback to a preferred server. For example, DFS link that has targets in both the branch and the hub, branch clients will automatically failover to the hub when the local server is unavailable.
For Windows Server 2003 R2, DFS failback functionality allows administrators to set server priorities for root and link target referrals, including setting high and low priority servers. In this case, servers are first ordered by site cost and then by priority within each site. Clients failback to the branch server when availability is restored.
DFS Namespace is administered by using the DFS Management Console that provides a hierarchical view of namespace. The DFS Management Console incorporates functionality that was previously only available through command line interface (CLI). The DFS Management Console applies features from Microsoft Management Console (MMC) 3.0, including built-in HTML reports and diagnostics.
Print Management Console
Through the Printer Management Console (PMC), administrators have a central interface for managing all printers connected to all print servers within an organization. With PMC, administrators can monitor printer errors, deploy printer connections to clients, automatically find and install printers on a local branch office subnet, and run configuration scripts. PMC allows branch servers to perform as print servers because they are remotely manageable on a one-to-many basis.
PMC is an MMC snap-in that enables administrators to view and manage all the printers on every print server in administrators’ organization from any computer on the network running Windows Server 2003 R2. PMC provides up-to-the-minute details such as the queue status, printer name, number of jobs, driver name, and server name. By using the PMC filtering capability, administrators can set custom views. For example, administrators could view only those printers in a particular error state or only printers in a specific location that have more than one job in the queue.
Filtering by error state also allows administrators to manage multiple queues at once. For example, administrators can select more than one printer and then cancel, pause, or resume all the print jobs simultaneously. Administrators can also delete multiple printers at the same time.
The automatic detect feature finds and installs printers from the local subnet to the local print server. Administrators can log on to a branch location's local server by using Remote Desktop and use this feature to easily install printers remotely.
In cases where a printer has a printer Web page, PMC may display rich troubleshooting details such as exactly where a paper jam is happening or the printer’s toner level. Some printer Web pages give the Administrator options for remote control functions that can help resolve problems at branch locations. By using the PMC, the printer Administrator may have a clearer picture of the problem before assistance is needed.