how to upgrade to hotfix on Big F5 11.3

I have been into the same scenario like this to upgrade Active/standby unit to version 11. That was from version 10.0 to 11.3. One issue i faced on one of our first site was that both of units go in active active mode and caused outage.

There are Two ways to complete this upgrade with out any outage in Production Environment. First if you can shut standby unit Ethernet Ports not management. Also consider not doing this if you are using network fail-over. Upgrade the system. after upgrade of Standby Unit Validate your configurations like no of VIPs and pools. Now the tricky part. shut down Ethernet ports on active unit and open ports on standby unit on which hotfix 8 is applied. also clear arp on both units. This is a risky way if you have any socket based traffic on your units.

Second way to do this is go to standby device, Install Hotfix, before rebooting device make that device forced offline. reboot the system. release offline. make sure its comes in standby. now go to device Active Unit and make that force standby making it standby. Validate both units are in active standby unit. repeat Upgrade steps on this unit same as previous one.

Considerations during Upgrade: Sync Configurations between both units. Reactive License on both units. For each device, Disable VLAN FailSafe. For each device, Disable Gateway Failsafe. For each device, set redundancy state preference to none. Take back file for both units.