Summary

This document provides steps configuring an Overlay IP as a Virtual IP address for HADR and Mutual Failover cluster on AWS with Db2 V11.5.8.0 and later. Previously the Pacemaker Overlay IP resource was configure via multiple 'crm' commands. In 11.5.8.0, new db2cm commands were introduced to automate configuration of the Overlay IP resource.

For releases prior to V11.5.8.0, refer to the original document: https://www.ibm.com/support/pages/node/6359155

Setting up Virtual IP (VIP) for HADR enabled database provides a common connection point for clients without the need to disclose the actual IP address of the primary and standby server for the database. If a failover occurs, the client can still connect to the new primary by using the VIP, effectively achieving automatic client reroute at the network level. The prerequisite for VIP setup is for the primary and standby servers' IP address to be on the same IP subnet - a requirement that sometimes cannot be easily achieved on cloud servers.

On AWS, Overlay IP address provides the capability to route network traffic between availability zones to the HADR servers within the AWS VPC by utilizing a route table entry. Effectively, that means one can set up the clients within the same AWS VPC but different availability zones as the Db2 HADR servers and establish connectivity through the Overlay IP address. For clients located in another VPC, or outside the AWS Cloud entirely, additional configuration using AWS Transit Gateways (TGWs) Network Load Balancers, or AWS VPN are required to connect to the Overylay IP.

Similar to standard virtual IP addresses, the Overlay IP address can only be associated with a single HADR database or Mutual Failover instance. In the case of HADR, an optional standby Overlay IP address can also be associated with the standby database to accommodate the HADR reads on standby feature. When configuring multiple Overlay IP addresses, each address will need its own route entry configured in the subnets routing table.

The goal of this document is to provide step-by-step procedures to set up a Db2 HADR configuration with Pacemaker on AWS with Overlay IP address Routing. The configuration of features such as AWS TGW, Load Balancers, or VPN are out of the scope of this document.

Note: For primary and standby VIP configuration in Db2 HADR with Pacemaker on AWS, the Overlay IP solution in this technote must be used instead of the VIP configuration created by using the db2cm tool.