Red Hat DIRECTORY SERVER 7.1 - DEPLOYMENT Deployment Manual page 103

Each database link is associated with a remote server holding data. You can also
configure alternate remote servers containing replicas of the data for the database
link to use when there is a failure. For more information on configuring database
links, refer to the Red Hat Directory Server Administrator's Guide.
Database links provide the following features:
• Invisible access to remote data.
Because the database link takes care of client requests, data distribution is
completely hidden from the client.
• Dynamic management.
You can add or remove a part of the directory from the system while the entire
system remains available to client applications. The database link can
temporarily return referrals to the application until entries have been
redistributed across the directory. You can also implement this functionality
through the suffix itself, which can return a referral rather than forwarding a
client application to the database.
• Access control.
The database link impersonates the client application, providing the
appropriate authorization identity to the remote server. You can disable user
impersonation on the remote servers when access control evaluation is not
required. For more information on configuring database links, refer to the Red
Hat Directory Server Administrator's Guide.
NOTE
If chaining is configured between a current version multiplexor and
a 4.x farm server, add the
server schema. If this attribute is not added to the 4.x Directory
Server schema, the current version multiplexor will not find the
entry it expects, and chaining will fail.
To add the attribute type to the 4.x schema, add the following line to
the 4.x farm server's
serverRoot/slapd-serverID/config
attribute nsuniqueid nsuniqueid
2.16.840.1.113730.3.1.542 int single operational
attribute to the 4.x farm
nsuniqueid
slapd-user_at.conf
directory:
Chapter 5
About Knowledge References
file under the
Designing the Directory Topology 103