The device priority does not help you in split-brain situations. Split-brain is, as described by @TranceforLife, when the firewalls cannot communicate, so both peers assume the other one is down -> both change to active state. The device priority is primary needed if you have one firewall which should, in most cases, handle the traffic. So in combination with preemptive mode, this makes sure that after a problemsituation is solved, the firewall with the higher priority (lower value) will change back to active. If you don't care which firewall is active, there is actually no need to set different values (even if I recommend to do it anyway), because if both firewalls have the same value, the one with the lowest mac address will become the active clustermember. @jdprovine If you need to reboot the firewall after a split-brain to restore full functionality of the cluster, this sounds to me like a bug ... do you have PAN-OS 8.0.1 running?
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