Specifications

Chapter 4 Open Directory Planning and Management Tools 63
Load Balancing in Small, Medium, and Large Environments
Do not use service load-balancing software from third parties with Open Directory
servers.
Load-balancing software can cause unpredictable problems for Open Directory
computers. It can interfere with the automatic load balancing and failover behavior
of Open Directory in Mac OS X and Mac OS X Server.
Mac OS X computers seek the nearest available Open Directory server—master or
replica. A computer’s nearest Open Directory master or replica is the one that responds
most quickly to the computer’s request for an Open Directory connection.
Replication in a Multibuilding Campus
A network that spans multiple buildings might have slower network links between
buildings than the link within each building. The network links between buildings
might also be overloaded.
These conditions can adversely aect the performance of computers that get Open
Directory services from a server in another building. As a result, you may want to set
up an Open Directory replica in each building.
Depending on need, you may even want to set up an Open Directory replica on
each oor of a multistory building. Each replica provides ecient directory and
authentication services to client computers in its vicinity. The computers do not need
to make connections with an Open Directory server across the slow, crowded network
link between buildings.
Having more replicas has a disadvantage. Replicas communicate with each other and
with the master over the network. This network communication overhead increases
as you add replicas. Adding too many replicas can add more network trac between
buildings in the form of replication updates than it removes in the form of Open
Directory client communications.
When deciding how many replicas to deploy, consider how heavily the computers
will use Open Directory services. If the computers are relatively light users of Open
Directory services and your buildings are connected by fairly fast network links (such
as 100 Mbps Ethernet), you probably do not need a replica in each building.
You can reduce the communication overhead between Open Directory replicas and
the master by scheduling how often the Open Directory master updates the replicas.
You might not need the replicas updated every time a change occurs in the master.
Scheduling less frequent updates of replicas will improve network performance.