Maintenance mode

borpin · 2018-11-16T14:44:55.883Z

Is there a ‘right’ way to do system maintenance on a running system?

Services to stop (is there a correct order?)

webserver (lighttpd/apache)
mysql (mariadb)
php
redis
mqtt_input
service-runner
feedwriter (if installed)

Anything missed?

TrystanLea · 2018-11-16T22:37:06.338Z

Hello @borpin

I usually stop services in the following order on an emonpi/emonbase:

emonhub & apache (stops incoming data at the source)
mqtt_input (receives data usually from emonhub)
feedwriter (receives data from mqtt_input)

Redis should not need stopping. But you can run a redis background save and then stop redis at this point if you want to be really safe before a reboot (e.g on emoncms.org).

mysql and php should not need stopping.

You can stop and restart emonhub, mqtt_input and feedwriter independently at any time. They talk together via MQTT and Redis.

mqtt_input handles reconnection if the mqtt broker goes down and exits if redis goes down. It then restarts automatically when redis-server is back up again. feedwriter does not seem to be restarting here, will look into that.