When a gateway reboots and there were active alarms before the shutdown, those alarms get activated again on startup…as it should by design (unless you select the option not to). However, what I am noticing on Ignition 8.1 is that if you have an Alarm configured to have a Label property read from other tags (such as an OPC tag containing the tag description), the alarm gets triggered before it had a chance to read that OPC tag. If you restart the tag, then the alarm clears and gets set again with the proper Label.
Here is an example:
Lets say your Label property is {[.]Cfg_Desc} + " Hi Alarm". After a reboot, the alarm will just read “Hi Alarm”. If you restart the tag, then the Alarm will read “Tank pH Hi Alarm”.
Now, Cfg_Label is set to a different (slower) scan class (sorry…Tag Group) because well, these values hardly ever change. But the point is that ALL tags should be read at least 1 time before evaluating alarms. I didn’t see this on Ignition 7.9 so this must be a new behavior of 8.x.