Add 2 additional servers (servers can not have NAT between them). Note that I personally add one server at a time.
Note: Primary server should be rebooted and NTP should be sync'd and configured before adding secondaries (
Jira server sipXcom and swarmcom Issue Tracker serverId b70c26b9-47bf-3f90-8285-702826eeed42 key SIPX-637
Install servers 2 and 3.