The reboot option in the GUI does a simultaneous reboot.  Turns out there's not an option for doing this outside of an upgrade. You could script it but unless there are lots of nodes I'd probably reboot them one at a time and confirm the node is back up and looking fine before moving on to the next node.    Timothy Write added the following to a similar question;Indeed, it is scriptable but I can't think of anything we ship that can do this out of the box. With the python libraries we supply it's probably easy enough to do.  In a past life, I had a bunch of shell scripts to do this kind of thing for testing purposes.
A team member asked me; I have a customer that has a bug that requires them to perform a rolling reboot.  What is the process for doing this … reboot one node at a time?  If you select "reboot the cluster" in the GUI, does that perform a rolling reboot or full reboot?
Rolling reboot without doing an upgrade