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7.
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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
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