Creating an inter-pod communication network for Db2 Warehouse

You can improve the throughput of fast communications manager (FCM) traffic between the Db2® partitions on each pod in a Db2 Warehouse massively parallel processing (MPP) deployment by dedicating an additional IP address on each worker node for inter-pod communication.

About this task

You update the JSON file that is used by the database service with a list of the inter-node IP addresses and it changes your deployment to use hostNetwork for inter-pod traffic.

Procedure

  1. Open the db2u-json-cm ConfigMap object in edit mode: 
    oc edit cm db2u-json-cm -n ${PROJECT_CPD_INSTANCE}
  2. Type /fcm-ips to locate the fcm-ips section of the ConfigMap.
  3. Under the ibm-db2wh.json data option, change fcm-ips to "ip_address_1:ip_address_2:ip_address_3": 
    \"fcm-ips\": \"ip_address_1:ip_address_2:ip_address_3\"

    Where ip_address_1:ip_address_2:ip_address_3 is a colon-delimited list of IP addresses that are to be used for Db2 FCM traffic in the cluster.

    Note: The number of IP addresses that you provide must match the number of schedulable nodes that you plan to allocate for Db2 Warehouse MPP. So for example if you plan to use four nodes but only deploy Db2 Warehouse on three of them, you must still provide four IP addresses because the fourth node can be schedulable and also can be targeted during failover.
  4. Save the change and exit the ConfigMap.
  5. Delete the zen-database-core pod in order for the ConfigMap changes to be re-mounted to the volume. 
    oc delete po $(oc get po -n ${PROJECT_CPD_INSTANCE} | grep zen-database-core | awk {'print $1'}) -n ${PROJECT_CPD_INSTANCE}
    Note: If you reinstall or upgrade the Db2 service, these steps must be performed again.