I’ve been using Google Compute Engine for 2 months now, I have a bunch of stuff installed on it.
Just installed a new kernel, so a reboot is required. I'd like to know if
sudo reboot is safe. Meaning a reboot will not wipe out everything installed on the instance?
There’s nothing different in running
sudo reboot in a instance versus on your own server.
This action shouldn't cause any problems.
I believe the author was worried if the disk is persistent or not. Yes you can shutdown/start/reboot the instance and your data will persist.