Tandberg Data Viking FS-1500, Viking FS-1600, Viking FS-412 Distributed File System DFS, Overview

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7. Distributed File System (DFS)

7.1.Overview

One of the goals of information technology (IT) groups in medium and large organizations is to manage file servers and their resources efficiently while keeping them available and secure for users. As organizations expand to include more users and servers—whether they are located in one site or in geographically distributed sites—administrators find it increasingly difficult to keep users connected to the files they need. On one hand, storing files on distributed servers makes files available to more users and decreases latency and bandwidth use when the servers are located near users. On the other hand, as the number of distributed servers increases, users have difficulty locating files they need, and operational costs increase.

Administrators who manage these distributed, remote servers need a solution that helps them limit network traffic over slow WAN connections, ensure the availability of files during WAN outages or server failures, and ensure that branch servers are backed up correctly. The Distributed File System solution in the Microsoft® Windows Server™ 2003 R2 operating system helps administrators address these challenges by providing two technologies, DFS Namespaces and DFS Replication, which, when used together, offer simplified, fault-tolerant access to files, load sharing, and WAN-friendly replication.

•DFS Replication is a new state-based, multimaster replication engine that supports replication scheduling and bandwidth throttling. DFS Replication uses a new compression protocol called Remote Differential Compression (RDC), which can be used to efficiently update files over a limited-bandwidth network. RDC detects insertions, removals, and re-arrangements of data in files, thereby enabling DFS Replication to replicate only the changes when files are updated. Additionally, a function of RDC called cross-file RDC can help reduce the amount of bandwidth required to replicate new files.

•DFS Namespaces, formerly known as Distributed File System, allows 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.

The following figure illustrates how DFS Namespaces and DFS Replication work together. The processes marked 1 and 2 are described in more detail following the figure.

7-1 Tandberg Viking Series Storage Server Administration Manual