Configuring Network Parameters

The window and group network parameters determine how the replication mechanism groups entries to send them more efficiently over the network. These parameters affect how suppliers and consumers exchange replication update messages and acknowledgments. The parameters are configurable in every replication agreement, which allows you to tailor the replication performance according to the specific network conditions of each consumer.

Monitor the effects of any modifications that you make and adjust the parameters accordingly. Refer to Getting Replication Status for instructions. You do not need to interrupt replication to modify the window size and group size parameters.

Configuring Window Size

The window size (default value 10) represents the maximum number of update messages that can be sent without immediate acknowledgment from the consumer.

It is more efficient to send many messages in quick succession instead of waiting for an acknowledgment after each message. Using the appropriate window size, you can eliminate the time replicas spend waiting for replication updates or acknowledgments to arrive.

If your consumer replica is lagging behind the supplier, increase the window size to a higher value than the default, such as 100, and check replication performance again before making further adjustments. When the replication update rate is high and the time between updates is therefore small, even replicas connected by a local area network (LAN) can benefit from a higher window size.

To Configure Window Size

You can use DSCC to perform this task. For information, see Directory Service Control Center Interface and the DSCC online help.

1. Modify the window size.

   $ dsconf set-repl-agmt-prop -h host -p port suffix-DN consumer-host:consumer-port transport-window-size:value

   For example:

   $ dsconf set-repl-agmt-prop -h host2 -p 1389 dc=example,dc=com host1:1389 \ transport-window-size:20

Configuring Group Size

The group size (default value 1) represents the maximum number of data modifications that can be bundled into a single update message. If the network connection appears to be impeding replication, increase the group size to a higher value than the default, such as 10, and recheck replication performance.

When increasing the group size, make sure that the following are true:

• The window size is set significantly higher than the group size.

• The window size divided by the group size is much greater than the value for nsslapd-maxThreadsPerConn under cn=config on the consumer (typically twice as large).

  When the group size is set higher than 1, the supplier does not wait to fill a group before sending updates to the consumer.

To Configure Group Size

You can use DSCC to perform this task. For information, see Directory Service Control Center Interface and the DSCC online help.

1. Modify the group size.

   $ dsconf set-repl-agmt-prop -h host -p port suffix-DN \ consumer-host:consumer-port transport-group-size:value

   For example:

   $ dsconf set-repl-agmt-prop -h host2 -p 1389 dc=example,dc=com host1:1389 \ transport-group-size:10