At this point, we have our data located simultaneously on two servers. The second system can fulfill many possible roles. It can replace the current node in case of hardware failure, or allow us to perform server maintenance or upgrades with very little downtime.
Regardless of our intent, properly utilizing the second system is the key to a highly available database server. In this recipe, we'll discuss the proper method for activating the second server in a two-node pair so that we can make changes to one or both nodes.
