Hey Jeremy, the Linux host of a 128T node can be set up with any number of privileged and non-privileged users for administering the overall system. The 128T SW sets up `admin` user and `128t`, `128t-user` and `128t-admin` groups for the purposes of administration of the 128T SW.
If an enterprises Linux system administration practices don't call for a particular user scheme, then as a matter of convention we'll typically set up nodes with a `t128` privileged user for doing system administration (so that the root user isn't required for logins). Check to see if you have the `t128` user on your hosts, and that they are in the `wheel` group:
[user@host ~]$ groups t128
t128 : t128 wheel
If you've got that, then the `t128` user should be able to gracefully power down the system with something like this:
[user@host ~] sudo systemctl stop 128T && sudo shutdown -h now