IBM PureData System for Analytics support for split-brain detection and notification

Cause

Split-brain is a condition that occurs when the images of data on each IBM Netezza host begin to deviate independently from a common synchronization point. It typically occurs there is an interruption to the dedicated data synchronization network connection and users subsequently change data independently on each Netezza host. As a result, the two Netezza host images are different, and manual intervention is required to determine which host's image should be selected as the most appropriate version to use. Data updates made on the other host could be lost during the recovery process because there is no way to combine both sets of host data into a coherent image.

Important: Split-brain should not occur if clustering is enabled. The fencing controls should prevent users from changing the replicated data on the standby node. Allow DRBD management to be controlled by Heartbeat to avoid the split-brain problems. Split-brain should not occur if one of the two hosts is rebooted or shutdown as part of normal system maintenance, as the DRBD subsystem is designed to capture all of the changes that occur while that host is off the network and replay them when it becomes reachable again. However, if a split-brain problem occurs, the following message is written to the /var/log/messages file:

Split-Brain detected, dropping connection!