|Jive and High-Availability / Failover Behavior of HA Servers|
The length of an outage will depend on several factors.
In the event of a failover, the length of your outage will depend on whether or not the system can correctly redirect everything to the passive system, how long it takes for either the manual or automatic processes to run where you're switching DNS/IP addresses, and the time it takes to bring up the application servers in the passive-now-active system.
Therefore, do your best to ensure that you've set up everything correctly, as described in the Configuring Jive for High-Availability section.
To learn how to start up the system after a failover, be sure to read Starting Up After a Failover.