Configuring TCP/IP keepalive parameters for high availability clients

The recommended method of setting the keepalive parameters on the client is to use the keepAliveTimeout parameter in the db2dsdriver.cfg configuration file.

About this task

The values provided in these commands are suggested values, but you should fine-tune these settings based on your specific network and server capabilities.

Procedure

There are two methods to update the TCP/IP keepalive parameters:

Modify the db2dsdriver.cfg file.

To set this parameter, edit the db2dsdriver.cfg file and place the keepAliveTimeout line outside of the <acr> section, but still within the <databases> parent section. For example:

<configuration>
  <dsncollection>
    <dsn alias="D3D" name="D3D" host="DB2PS-member0" port="5912" />
  </dsncollection>
  <databases>
    <database name="D3D" host="DB2PS-member0" port="5912">
    <parameter name="keepAliveTimeout" value="20"/>
    <acr>
      <parameter name="enableAcr" value="true"/>
      <parameter name="enableSeamlessAcr" value="true"/>
      <parameter name="affinityFailbackInterval" value="15"/>
   </acr>
</database>

</databases>
...
</configuration>

This method is recommended because it can be used for both instance-based clients and drivers without an instance. In addition, by utilizing the db2dsdriver.cfg file, each individual database can have a different keepAliveTimeout setting.

Modify the DB2TCP_CLIENT_KEEPALIVE_TIMEOUT parameter
The second method for updating the keepalive parameters is to set the DB2TCP_CLIENT_KEEPALIVE_TIMEOUT parameter to detect failures in the TCP/IP communication layer.
To update this parameter, from a command window or terminal on the client, issue this command:
```
db2set DB2TCP_CLIENT_KEEPALIVE_TIMEOUT=20
```
This value is specified in seconds.
Note: While TCP/IP timeout keepalive is also supported for instance attachments, it can only be set using this second method of specifying a value for the DB2TCP_CLIENT_KEEPALIVE_TIMEOUT parameter. Note that automatic client reroute (acr) does not apply in the case of instance attachments.

Setting the operating system level parameters can help with early detection of a non-responsive socket at the remote end. For faster client reroute, configure the TCP/IP keepalive parameter settings at the operating system level.