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