[Nut-upsuser] Synology NAS is shutting down Ubuntu servers after very brief power outage

Todd Benivegna todd at benivegna.com
Sun Aug 2 22:00:41 BST 2020

How would I capture with Wireshark when it seemingly happens at random?  Whenever I test, everything appears to work normally.  I wish I could somehow replicate it.  Maybe I need to test manually and see if it’ll happen in front of me; I’ve never actually seen it happen… always happens when I’m away.

Todd Benivegna // todd at benivegna.com
On Aug 2, 2020, 12:12 PM -0400, Manuel Wolfshant <wolfy at nobugconsulting.ro>, wrote:
> On 8/1/20 11:25 PM, Todd Benivegna wrote:
> > I'm hoping that someone can shed some light on this… I have a Synology NAS (DS416) that has a feature where you can enable a “Network UPS Server” which is a NUT server.  I have been trying to get the Synology to shut down three Ubuntu 20.04 servers that I have. While it does work when I test it out manually, sometimes when I am away and the power goes out briefly, the servers shut down when the power has been out for like five seconds (or less sometimes).  When I come home and turn on the servers, they boot up but then immediately shut down again.  This happens until I restart the Synology; then they will boot up and stay up.  I‘d like them to stay up a little longer than that.  Ideally, I’d like them to stay up until battery is low, then shut down, then all come back on when power is restored.
> >
> > This is what I have done so far:  I have enabled "Enable Network UPS server" on the Synology and have installed NUT on each of my servers running Ubuntu 20.04.  I have added the appropriate IPs to the Permitted DiskStation Devices” list.  I have also tried setting it on the Synology to shut down when battery is low and after a specified amount of time (20 minutes).  Either way, the servers will shut down after like 5 seconds or less.  I have edited upsmon.conf and added my MONITOR line and setup systemctl so that the nut-client service starts automatically at boot.  I have no made any other changes to the file; the rest is still set to defaults.
> >
> > So I'm not sure where exactly the problem is; if it's the Synology or NUT on Ubuntu.  Strange thing is, when I manually test by shutting off the power briefly (or for a few seconds, or a few minutes - I've tried everything;) every time I do a test, everything works perfect and they will shut down when they are supposed to.  Seems to only happen when there is a passing storm that knocks the power out for a few seconds.
> >
> > Also, this is what I found in the syslog on one of the machines:
> > Jul 31 18:33:29 plex upsmon[970]: UPS ups at on battery
> > Jul 31 18:33:34 plex upsmon[970]: UPS ups at on line power
> > Jul 31 18:34:04 plex upsmon[970]: Executing automatic power-fail shutdown
> > Jul 31 18:34:04 plex upsmon[970]: Auto logout and shutdown proceeding
> > Jul 31 18:34:09 plex systemd[1]: nut-monitor.service: Succeeded.
> >
> > If I’m not mistaken, it is shutting down after power came back on line….?
> My first suspect is the Synology version of nut. More specifically, I suspect that nut triggers a shutdown immediately after the switch to "on battery" state and only cancels it after a restart.
> What I would do is to use wireshark to sniff the communication between the Synology and one of the Ubuntu machines and log what exactly ( and when ) is sent by the nut server to the clients. I'd also couple that with a bit of logging on the nut side as well ( for 60 secs or so, starting shortly before the switch to on-battery, with a very short interval between polls )
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