If it's a clean reboot, first shutdown all services possible, primarily those that depend on AFS, but others are also important as basically everything depends on user lookups and libnss-afs. So shutdown as much as you can, and it'll make reboot controlled and smooth.
To reboot, hook up to the IPKVM, open channel connected to Deleuze console, and from there, either reboot with sudo reboot as usual, or if it's hung, invoke the SysRq reboot as follows:
- Open "Keys" menu in the KVM
- There, select "LAlt" toggle-- it'll combine all keys you press with implicit Left-Alt. (And you can leave the Keys menu open while doing the rest of the steps, it won't interfere with the keystrokes you're sending.)
Press SysRq + s to invoke emergency sync
Press SysRq + b to reboot