ME4 4024 Best practice - Firmware update

Hi,

I am running a cluster with four hosts and a ME4024 dual controller storage.

I want to update the firmware without any downtime on the hosts.

So first I will check the health status via ssh:

check firmware-upgrade-health Upgrade Health

If the check is fine I will upload the firmware file via the gui. I have checked the administator guide and the best practice guide but there is no clear statement.

How can I be sure, that the firmware update is only running successfull on one controller and after that on the partner controller? I am afraid that it will run the update on both controllers at the same time.

Do I need to check or uncheck the PFU box?

Thanks!