Directory Structure

In a general-purpose directory, you have to decide what information you want to store, and how that information will be organized. The information in the global directory can be physically located on a number of different servers. However, it fits into a single overall tree structure.

Directory Information Tree

Information in the directory is organized in a tree structure, called the Directory Information Tree (DIT). The structure of a DIT usually reflects very closely the structure of the information it contains. For example, a directory containing entries for people in a corporation could be organized by division or by location. In general, DIT structures are organizational, geographical, or include both organizational and geographical factors. However, another possibility is to organize the DIT structure according to internet domains. The logical organization of the DIT into naming contexts is discussed in Chapter 3, Planning a Directory Service.

Data Stores and Naming Contexts

The directory information is divided into naming contexts. A naming context is a subtree of the directory, and is identified by the DN of the entry at the top of the subtree. A naming context is stored in a physical data store. A data store can hold more than one naming context. A directory server can contain more than one data store.

The naming contexts that identify the data store are called data store suffixes in the Sun Directory Services Admin Console.

When dividing the DIT into naming contexts and data stores to be held on individual servers, you need to take account of the following:

• A search cannot cross naming contexts or data stores. If you want to perform a search in several naming contexts, you have to define referrals between the data stores, or start several simultaneous search operations.

• Alias definitions are local to a naming context.

The Sun Directory Services data store can hold up to four data store suffixes, and one million entries. If you need to store more entries, you can install several data stores, on one or several servers, and create referrals between them. For more information on using Sun Directory Services to store more than one million entries, refer to "Referrals".