Tandberg Data NAS Hardware Viking FS-1500 - Manual (Page 92)

Tandberg Data Distributed File System
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7-2 Tandberg Viking Series Storage Server Administration Manual
As the figure shows, when a user attempts to access a folder in the
namespace (1), the client computer contacts a namespace server. The
namespace server sends the client computer a referral that contains a list of
servers that host the shared folders (called folder targets) associated with
the folder. The client computer caches the referral and then contacts the first
server in the referral (2), typically a server in the client’s own site unless no
same-site servers exist or the administrator configures target priority.
The highlighted folder in the figure shows that it is hosted by shared folders
on two servers, one in New York and one in London, to provide users in
those sites with fast, reliable access to files. The shared folders are kept
synchronized by DFS Replication. The fact that multiple servers host the
folder is transparent to users, who see only a single folder in the namespace.
If one of the servers becomes unavailable, the client computer fails over to
the remaining server.
7.2. DFS Namespaces
DFS Namespaces allows you to group shared folders located on different
servers by transparently connecting them to one or more namespaces. A
namespace is a virtual view of shared folders in an organization. When you
create a namespace, you select which shared folders to add to the
namespace, design the hierarchy in which those folders appear, and
determine the names that the shared folders show in the namespace. When
a user views the namespace, the folders appear to reside on a single, high-
capacity hard disk. Users can navigate the namespace without needing to
know the server names or shared folders hosting the data.
The path to a namespace is similar to a Universal Naming Convention
(UNC) path of a shared folder, such as \\Server1\Public\Software\Tools. If
you are familiar with UNC paths, you know that in this example the shared
folder, Public, and its subfolders, Software and Tools, are all hosted on
Server1. Now, assume you want to give users a single place to locate data,
but you want to host data on different servers for availability and
performance purposes. To do this, you can deploy a namespace similar to
the one shown in the following figure. The elements of this namespace are
described after the figure.