Deploy Virtual Appliances in Pairs
VAs must always be deployed in pairs. Running two or more VAs offers high availability in case of system updates. This ensures that there is no interruption in Internet service during an update, and allows you to configure updates for scheduled maintenance windows or off-hours.
-
No downtime associated with upgrades
When an upgrade takes place, individual virtual appliances will restart, causing up to 20 minutes of downtime. During this time, any DNS queries routed to the virtual appliance will time out and you will lose internet connectivity. Running two VAs ensures that there is no interruption in Internet service.
-
Ability to schedule updates
Running two VAs allows for scheduling updates. You can schedule updates for off-hours or during scheduled maintenance windows.
-
High availability
If issues arise in one of your VAs, or if you would like to rebuild or move a VA to another host, you can take action without interruptions.
To set up a second virtual appliance, repeat the procedure for setting up the first one. For more information, see Deploy Virtual Appliances.
Whenever possible, deploy VAs on separate physical hypervisor hosts. If a hypervisor hosting a VA becomes unavailable, the second VA will continue serving DNS requests without interruption.