No, if you are running failover, you won't be able to keep the failover active/enabled when you are upgrading the memory because failover checks that the memory must be the same to keep it active.
I would suggest that you:
- turn the failover off on both firewalls, save the config and shutdown the secondary firewall.
- upgrade the memory on the secondary firewall.
- power the secondary up and check that the memory has been upgraded (show version)
- when secondary is up, power the primary down.
- upgrade the memory on the primary firewall.
- power primary firewall up, and check that memory has been upgraded
- turn failover back on both firewalls.
There would be slight glitch in your network as failover is turned off so connection might be dropped and reinitiated through the firewall as the states are not synchronized. I would strongly suggest that this work is performed during a maintenance window.
Hope that helps.
