OSF DCE Administration Guide--Introduction

Introduction to DCE for Administrators
cell are usually located in a common geographic area, but they can also be located in
different buildings, different cities, or even different countries, provided they are
adequately connected. A cell’s size can range from only one machine to several
thousand, depending on the size of the organization. All machines in an organization can
be included in one cell, or you can choose to have numerous cells within one
organization.
Cells designate security, administrative, and naming boundaries for users and resources.
Each cell has a name. Cell names are established during the installation and
configuration of DCE components.
Members of an organization who are working on the same project are likely to belong to
the same cell. For example, in a large organization with several cells, the sales team
could belong to one cell, the engineers working on Project X could belong to a second
cell, and the engineers working on Project Y could belong to a third cell. On the other
hand, a small organization may have only one cell for both the sales force and the
engineers because they share the same level of security and the organization’s small size
does not warrant the additional administrative overhead that maintaining additional cells
requires.
DCE services are managed within the context of a cell, as described by the following
examples:
• Each DCE cell typically consists of at least one Cell Directory Service (CDS) server,
three Distributed Time Service (DTS) servers, and one Security Service server, as
well as the databases that the CDS and Security servers use.
• Pathnames of DCE objects managed by DCE services can be expressed relative to
the cell where the objects reside.
• DTS has both local and global servers. Local servers operate within a Local Area
Network (LAN). Global servers provide time services anywhere within the cell.
1.4 The Namespace
The namespace is the hierarchical set of names of DCE objects. The top levels of the
hierarchy are managed by the Directory Service. Some DCE services (currently the
Security Service and Distributed File Service (DFS)) manage their own portions of the
namespace. Each DCE object in the namespace consists of a name with associated
attributes (pieces of information) that describe its characteristics. These objects include
resources such as machines or applications.
The namespace contains global namespaces and cell namespaces. A cell namespace
includes objects that are registered within a cell. A logical picture of a cell namespace is
a hierarchical tree with the cell root directory at the top and one or more levels of
directories containing names beneath the cell root. The cell namespace is managed by
the Cell Directory Service (CDS) component of the Directory Service. Conversely, the
global namespace, as seen from a local DCE cell, contains objects that are registered
outside the local cell, such as the names of other cells. The Global Directory Service
(GDS) component of the Directory Service manages one part of the global namespace; a
non-DCE service called the Domain Name System (DNS) manages another part of the
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