Citeren Thomas Gutzler <[email protected]>:

So when the batteries are critical, the master
- sends out FSD to all slaves and touches POWERDOWNFLAG
- waits for slaves to disconnect or max HOSTSYNC seconds to pass
- waits another FINALDELAY seconds
- executes its SHUTDOWNCMD, which
  - stops upsd, the drivers and the master upsmon (K50nut)
  - stops the nfs server (K80nfs-kernel-server)
  - runs upsdrvctl shutdown (S90halt) to shut down the UPSes

When a slave detects a FSD, it
- processes NOTIFY_SHUTDOWN (send an email in my case)
- waits for FINALDELAY seconds
- executes its SHUTDOWNCMD instantly, which
  - unmounts all nfs drives (S31umountnfs.sh)
  - causes upsmon to disconnect and stop (K50nut) and
  - shortly after powers off the system (as long as it takes to execute
the remaining few shutdown scripts)

If that's correct, isn't it better to set FINALDELAY to 0 and increase
HOSTSYNC for all slaves rather than increasing FINALDELAY for the
master? Shouldn't HOSTSYNC be the time the slowest slave needs to get to
the nut shutdown script after receiving a shutdown, which can be delayed
by up to POLLFREQALERT seconds?

The above may work, provided the kill script for NUT isn't run before the NFS drives have unmounted. In your setup, this may be true, but this may not be so in the general case. Also, the behavior of NUT clients when they see the FSD flag is explicitly not defined. They may logout from the server immediately and start shutting down only after that. A 'FINALDELAY 120' on the NFS system guarantee at *least* 120 seconds for the clients to unmount their NFS drives from the moment the FSD flag is set. Using 'HOSTSYNC 120' guarantees at *most* 120 seconds (but it could be lower as well), so we don't recommend that.

You can't use POLLFREQALERT to delay the shutdown. This is meant to be able to use different upsmon polling intervals, depending on the power state of the UPS they are monitoring. You may choose to poll less frequently (60 seconds) when the mains is present and poll more frequently (5 seconds) when the mains is out. On a upsd server with only six clients attached, the clients will cause a negligible load regardless of the poll interval, so changing this will bring you no nothing. You'll need several hundreds of clients polling every 5 seconds each to be able to see a noticeable difference in the load.

Best regards, Arjen
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