I have an APC Switched Rack PDU powering a number of servers in a remote datacentre. After a recent power outage, I noticed that the outlets did not automatically default to the On status once power was restored. Having reviewed the Web UI, I cannot find this option.

I'm not certain of the model number (it doesn't appear to be visible in the Web UI), but I think it's this one.

Is it possible to configure these PDU units to automatically power outlets after a cold start?

  • Which model do you have?
    – Chopper3
    Oct 30, 2010 at 11:03
  • Edited to include the details of the model. Oct 30, 2010 at 11:35
  • on the manufacturers site in features is written that you can specify the order of machines powered on. Maybe you just have too high delays set? Oct 30, 2010 at 12:47
  • 1
    be careful, once i got a near-disaster experience when after a long blackout, the power came back for less than a minute and back off before there was any charge in the batteries. some servers did came up and down uncleanly. we rewired everything and now restarting the systems need human intervention
    – Javier
    Oct 30, 2010 at 13:05
  • I, too, had such an experience like that with power coming back for a couple minutes and then going away. Poor servers.
    – Rob Olmos
    Oct 30, 2010 at 20:35

2 Answers 2


I've only done this via SNMP set commands and I've only disabled it so the ports DON'T power on after a power failure as I've also been in the power-off/power-on/power-off situation.

snmpset -v1 -c $COMMUNITY $PDU . i -1

This tells the outlets NOT to turn on after a power failure. Change the -1 to 60 to turn all of the outlets on after 60 seconds. On the switched models you can also do a staggered start of the outlets in order to avoid a circuit overload situation. I don't have that OID handy.


As has already been mentioned, this is a disaster aversion function.

You don't mention your software environment or management topology.

In the case that it's 'apcupsd', which is the standard APC UPS management application for linux, this would be configured on the master node in file /etc/apcupsd/apcupsd.conf.

To acheive what you inquired about, the pertinent section would need to look like this:

# Battery charge needed to restore power
# RETURNCHARGE 00 15 50 90 (default = 15)

Values are in percents.

This value ought to be set such that even if power fails immediately after powering up the server(s), there remains enough charge to provide power through the entirety of both startup & shutdown sequences.

Ultimately it's your call.

Maybe you have backup generators on-site, which is what comes to mind when I wonder what would warrant such a configuration.

  • Hi - my question is around the PDU, not the UPS Dec 7, 2010 at 14:57

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