OSF DCE Administration Guide--Core Components

Chapter 12. CDS Concepts
The Cell Directory Service (CDS) is a high-performance distributed service that provides
a consistent, location-independent method for naming and using resources inside a cell.
CDS offers the ability to replicate CDS names; that is, to store copies of them on more
than one node. CDS automatically keeps multiple copies consistent. Names also can be
distributed among several nodes so that no one node has to store all of them. This
feature is particularly valuable in large cells.
The ability to replicate and distribute information has many benefits, including the
following:
• Availability—Because you can store the same name in more than one place, data is
likely to be available even in the event of a system or network failure.
• Efficiency—CDS finds names efficiently because you can store them close to where
they are used most often. Furthermore, once CDS finds a name, it can connect to the
same name immediately on all subsequent lookups.
• Load Sharing—Because names are in more than one place, several systems can share
the load of looking them up.
• Expandability—New names are easily accommodated as the network grows and
more applications use CDS.
12.1 How CDS Works
Operation of the CDS involves several major participants:
• client applications
• servers
• clerks
• clearinghouses
CDS uses a client/server model. An application that depends on CDS to store and
retrieve information for it is a client of CDS. Client applications create names for
resources on behalf of their users. Through a client application, a user can supply other
124243 Tandem Computers Incorporated 12−1