you should always set HA2 as without session sync failovers are dramatic.
It is the core reason to have a cluster in the first place: seamless failover
Without ha2 you can just as well set up 2 standalone devices and do ospf or install a load balancer ;) )
there is no recommendation to have HA2-backup in the panw best practices (also not one for HA1-backup, but please take my word that this is a must, you can use the mgmt interface if no physical interface is available))
you should always set HA2 as without session sync failovers are dramatic.
It is the core reason to have a cluster in the first place: seamless failover
Without ha2 you can just as well set up 2 standalone devices and do ospf or install a load balancer ;) )
there is no recommendation to have HA2-backup in the panw best practices (also not one for HA1-backup, but please take my word that this is a must, you can use the mgmt interface if no physical interface is available))