To set up a functional HA, it is important to have all the virtual machines on a shared storage. Proxmox HA only handles Proxmox nodes and virtual machines within a Proxmox cluster. These HA features are not be confused with shared storage redundancy, which Proxmox can utilize for it's HA deployment. A third-party shared storage may provide its own HA features.

There can be levels of redundancy in a Proxmox computing node, such as the use of RAID, redundant power supply, aggregated network link or bond, and so on. HA in Proxmox is not a replacement for any of these layers. It just facilitates redundancy features for virtual machines to keep running during a node failure.

It should be noted that in a Proxmox node, a reboot due to an applied update will cause all HA-enabled virtual machines to shut down and move to the next available Proxmox node and restart again. In such a situation, it may be necessary to manually live migrate virtual machines first, which requires...