Specifications

48 Chapter 4 Open Directory Planning
Having more replicas does have 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 actually add more network
traffic between buildings in the form of replication updates than it removes in the form
of Open Directory client communications.
Therefore in deciding how many replicas to deploy, you must consider how heavily the
client computers will use Open Directory services. If the client computers are relatively
light users of Open Directory services on average and your buildings are connected by
fairly fast network links (such as 100 Mbit/s 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 performance of the network.
Improving Performance and Redundancy
You can improve the performance of Open Directory services by adding more memory
to the server and having it provide fewer services. This strategy applies to every other
service of Mac OS X Server as well. The more you can dedicate an individual server to a
particular task, the better its performance will be.
Beyond that general strategy, you can also improve Open Directory server performance
by directing the LDAP database to its own disk volume and the Open Directory logs to
another disk volume.
If your network will include replicas of an Open Directory master, you can improve
performance of the network by scheduling less frequent updates of replicas. Updating
less frequently means the replicas have less up-to-date directory data. You have to
strike a balance between higher network performance and less accuracy in your
replicas.
For greater redundancy of Open Directory services, you can set up additional servers as
Open Directory replicas. Another strategy for increasing redundancy is to use servers
with RAID sets for Open Directory services.
LL2352.Book Page 48 Friday, August 22, 2003 3:12 PM