Creating Custom Schema Files - Red Hat DIRECTORY SERVER 8.1 - DEPLOYMENT Deployment Manual

Chapter 3. Designing the Directory Schema
might prevent the entries that use the object class from being modified later. Schema checks on
modified entries also fails unless the unknown object class values are removed from the entry.

3.4.7. Creating Custom Schema Files

Administrators can create custom schema files for the Directory Server to use, in addition to the
99user.ldif file provided with Directory Server. These schema files hold new, custom attributes
and object classes that are specific to the organization. The new schema files should be located in the
schema directory, /etc/dirsrv/schema.
All standard attributes and object classes are loaded only after custom schema elements have been
loaded.
NOTE
Custom schema files should not be numerically or alphabetically higher than
99user.ldif or the server could experience problems.
After creating custom schema files, there are two ways for the schema changes to be distributed
among all servers:
• Manually copy these custom schema files to the instance's schema directory, /usr/lib/dirsrv/
slapd-instance_name/schema. To load the schema, restart the server or reload the schema
dynamically by running the schema-reload.pl script.
• Modify the schema on the server with an LDAP client such as the Directory Server Console or
ldapmodify.
• If the server is replicated, then allow the replication process to copy the schema information to each
of the consumer servers.
With replication, all of the replicated schema elements are copied into the consumer servers'
99user.ldif file. To keep the schema in a custom schema file, like 90example_schema.ldif,
the file has to be copied over to the consumer server manually. Replication does not copy schema
files.
If these custom schema files are not copied to all of the servers, the schema information are only
replicated to the replica (consumer server) when changes are made to the schema on the supplier
server using an LDAP client such as the Directory Server Console or ldapmodify.
When the schema definitions are replicated to a consumer server where they do not already exist,
they are stored in the 99user.ldif file. The directory does not track where schema definitions are
stored. Storing schema elements in the 99user.ldif file of consumers does not create a problem as
long as the schema is maintained on the supplier server only.
If the custom schema files are copied to each server, changes to the schema files must be copied
again to each server. If the files are not copied over again, it is possible the changes will be replicated
and stored in the 99user.ldif file on the consumer. Having the changes in the 99user.ldif file
may make schema management difficult, as some attributes will appear in two separate schema files
on a consumer, once in the original custom schema file copied from the supplier and again in the
99user.ldif file after replication.
For more information about replicating schema, see
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Section 6.4.4, "Schema Replication".