High availability (HA) is the ability of a system to maintain a high uptime even in the presence of infrastructure failures.
A significant factor affecting a software system availability is hardware failure in underlying server executing the software. In the past, implementing hardware-related high availability for application software often involved running two or more instances of the software on different servers and having them synchronized so that one instance would take over in case the other instance failed.
In the past decade, virtualization technology has decoupled software from the underlying hardware infrastructure. If a specific piece of hardware fails, the virtualization layer can automatically move the software workload elsewhere, with minimal interruption of service. This greatly simplified the implementation of hardware-related HA, eliminating the need of maintaining multiple instances of the application to achieve high-availability requirements in most environments.
Lighthouse is packaged as a virtual appliance, which means it runs as a virtual machine and inherits the high availability attributes from the virtualization layer. For most environments, Lighthouse already has sufficient HA capabilities by leveraging the availability attributes of the virtualization infrastructure.
Geographical redundancy and disaster recovery (DR)
Certain environments may have exceptionally high requirements for availability with business continuity plans that involve resilience against major natural disasters, massive network disruptions, catastrophic destruction of entire facilities, etc. Those environments might still require the deployment of multiple instances of the software application, typically across multiple geographical locations.