When a node joins the cluster, the cluster performs a check to see which node has the best configuration. It asks the node with the highest (
admin_epoch
,
epoch
,
num_updates
) tuple to replace the configuration on all the nodes — which makes setting them, and setting them correctly, very important.
admin_epoch
is never modified by the cluster; you can use this to make the configurations on any inactive nodes obsolete.
Never set this value to zero. In such cases, the cluster cannot tell the difference between your configuration and the "empty" one used when nothing is found on disk.