# Add Child Server Groups

In non-mirror mode, you can configure DAH with child server groups. Each child server group contains a set of mirrored child servers. DAH contacts only one of the child servers in the mirror group for each action, according to your configured `DistributionMethod`.

NOTE: If you use child server groups, you cannot also use virtual databases.

To add a child server mirror to an existing child server

1. Open the DAH configuration file in a text editor.

2. Find the section where you configure your child servers (`[DAHEngineN]`, `[DistributedEngineN]`, or `[IDOLServerN]`).

3. In the `Host` parameter, add the host names or IP addresses of the mirrored child servers. Separate multiple names with commas.

       Host=host1,host2

4. In the `Port` parameter, add the ports of the mirrored child servers, separated with commas. The first port must correspond to the first value in the `Host` parameter, the second port must correspond to the second value in the `Host` parameter, and so on.

       Port=9100,9100

5. If you use the `HostPortAlias`, `Krb5Service`, or `Krb5Realm` configuration parameters, update these parameters to specify a value for each mirror.

       HostPortAlias=12.3.4.56:9100,23.45.67.12:9100
       Krb5Realm=COMPANY.COM,COMPANY.COM
       Krb5Service=IDOL,IDOL

6. (Optional) If you use the `Weight`, `Priority`, or `SSLConfig` parameters, you can specify a value for each child server. If you use a single value, all child servers in the group use the same value.

       Weight=75,25
       Priority=4
       SSLConfig=SSLOption3

7. If you have set `UseEngineAlias` to `True` in the `[Server]` section, add the `MirrorName` configuration parameter to the child server configuration. Set this parameter to a comma-separated list of aliases. You must configure an alias for each child server.

       MirrorName=childserver1,childserver2

8. Save and close the configuration file.

9. Restart the DAH for your changes to take effect.

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