hi ' i was wondering if the proccess of upgrading to the latest firmware version 5 needs an array restart or can i do it online with all hosts connected to the array with mpio configured?
do i need to schedule a downtime?

I have done firmware upgrades on the Equallogics without having to Shutdown any of the Host. Not on Firmware 5, but on Firmware 4.3.6. I did this as a test to see how it would work, on an Enviroment that didn't have anything Critcal servers running at the time. It worked without a hitch. It upgraded one Controller and then kicked over to the secondary Controller, then once the other controller came back, it upgraded the secondary controller. I didn't as much as lose one ping. But it is recommended that you schedule a downtime.