What is the purpose of having dual switches for a private network in the Db2 pureScale cluster?
The main reason is that a single switch means a single point of failure. If the switch were to fail, it would result in the loss of the entire cluster. With dual switches, the chance of critical failure is reduced due to improved network resiliency over the single switch configuration. That is why dual switches are the recommended best practice configuration.
There are specific physical network connectivity requirements between the switches and between the switch and Db2 hosts in a dual switch configuration. For more information, refer to Network topology configuration support for Db2 pureScale environment, and check the “Two-switch configuration with multiple RDMA communication adapter ports“ section in the page.