The Cell Directory Service (CDS) server runs on a node containing a database of directory information, called a clearinghouse. CDS information is contained in three types of data elements:
· Directory entries
A directory entry consists of a name and its attributes.
· Directories
A CDS directory is a logical grouping of CDS information; it is a collection of directory entries. The directory is the administrative unit for replication. There can be one or more copies, or replicas, of a given directory. CDS directories are in a hierarchical relationship to one another; each directory has a parent directory and may also have child directories.
· Clearinghouses
A clearinghouse is a physical CDS database; it is a collection of directory replicas. The clearinghouse is the database on a CDS server machine that the CDS server accesses in order to respond to its requests.
A directory service must be highly available, since other services depend on it. CDS achieves availability through replication of directories and consistency among copies of data. Two types of directory replicas exist in CDS:
· Master Replica
There is exactly one master replica of a given directory. You can perform any kind of operation on a master replica.
· Read-Only Replica
The only operations you can perform on a read-only replica are those limited by read access to the directory; you cannot make any updates to this replica.
For complete information about CDS, refer to the online help files.
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