Chapter 8. Tuning the Replication Performance

8.1. Improving the Multi-Master Replication Efficiency

The replication latency in a multi-master replication environment, especially if the servers are connected using a wide area network (WAN), can be high in case of multiple masters are receiving updates at the same time. This happens when one master exclusively accesses a replica without releasing it for a long time. In such situations, other masters cannot send updates to this consumer, which increases the replication latency
To release a replica after a fixed amount of time, set the nsds5ReplicaReleaseTimeout parameter on replication masters and hubs. For example, to set a 60 seconds timeout, enter:
[root@server ~]# ldapmodify -D "cn=Directory Manager" -W -x

dn: cn=replica,cn=dc\3Dexample\2Cdc\3Dcom,cn=mapping tree,cn=config
changetype: modify
replace: nsds5ReplicaReleaseTimeout
nsds5ReplicaReleaseTimeout: 60
The 60 second default value is ideal for most environments. A value set too high or too low can have a negative impact on the replication performance. If the value is set too low, replication servers are constantly reacquiring one another and servers are not able to send many updates. In a high-traffic replication environment, a longer timeout can improve situations where one master exclusively accesses a replica. However, in most cases, a value higher than 120 seconds slows down replication.