To expand on the official procedure from the admin guide... It just states to shut down the engines before the SDA. However, at which point is it safe to proceed to shutdown the next engine? Can I shutdown all engines essentially at once? Or it's important to wait for the yellow status before proceeding to the next engine? Or for it to disappear from the engines list?

The official answer I got from support was to ping the engines and move to the next one once the pings stop coming back... which is a handy hack, but is that really the best proper procedure? Of course the most important time one needs to shutdown a Nexis is when there's a power outage and seconds tick by as you ache to get it safed before your UPS batteries run out. So this stuff really matters.https://19216811.cam/  https://1921681001.id/

I also wish the Nexis shutdown/restart process is a bit more elegant. Maybe a way to stop the file system too?

 

This is a thread on the topic. I'll repeat what I said:

The issue is if the SDA or engine running the System Director is shutdown first, you won't have access to the other engines except to connect via the management port. This is the only reason to shut them down first.

There's no reason I can think of to not shut all the engines down at the same time, it doesn't matter. After that you can shut the system director down.