Skip to content

APC CS-500 causes USB disruption

I’m having a EM interference problem with the APC CS-500 UPS on two different locations. Those two locations are near each other and there seems to be something wrong the power grid in that area. Both UPS’s momentarily switch over to battery several times a day. Some of these times, the apcupsd daemon sends a message saying that the communication with the UPS has been restored (and therefore it had been lost at some point).

Here is the syslog of one of those computers with everything but the power failure and EMI notices filtered out:

Aug  7 06:59:10 bitler apcupsd[22622]: Power failure.
Aug  7 06:59:18 bitler apcupsd[22622]: Power failure.
Aug  7 06:59:31 bitler apcupsd[22622]: Power failure.
Aug  7 06:59:35 bitler apcupsd[22622]: Power failure.
Aug  7 13:59:19 bitler apcupsd[22622]: Power failure.
Aug  7 13:59:38 bitler apcupsd[22622]: Power failure.
Aug  7 18:59:11 bitler apcupsd[22622]: Power failure.
Aug  7 18:59:25 bitler apcupsd[22622]: Power failure.
Aug  7 18:59:28 bitler apcupsd[22622]: Power failure.
Aug  7 21:29:12 bitler apcupsd[22622]: Power failure.
Aug  7 21:29:19 bitler apcupsd[22622]: Power failure.
Aug  7 21:29:23 bitler apcupsd[22622]: Power failure.
Aug  7 21:29:51 bitler apcupsd[22622]: Power failure.
Aug  7 21:30:05 bitler apcupsd[22622]: Power failure.
Aug  7 21:30:09 bitler apcupsd[22622]: Power failure.
Aug  7 21:30:12 bitler apcupsd[22622]: Power failure.
Aug  7 21:30:14 bitler apcupsd[22622]: Power failure.
Aug  7 21:35:21 bitler apcupsd[22622]: Power failure.
Aug  7 21:35:29 bitler apcupsd[22622]: Power failure.
Aug  7 21:35:32 bitler apcupsd[22622]: Power failure.
Aug  7 21:35:38 bitler apcupsd[22622]: Power failure.
Aug  7 22:39:11 bitler apcupsd[22622]: Power failure.
Aug  7 22:39:22 bitler apcupsd[22622]: Power failure.
Aug  7 22:39:31 bitler apcupsd[22622]: Power failure.
Aug  7 22:39:35 bitler apcupsd[22622]: Power failure.
Aug  7 22:39:36 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  7 22:59:10 bitler apcupsd[22622]: Power failure.
Aug  7 22:59:25 bitler apcupsd[22622]: Power failure.
Aug  7 22:59:28 bitler apcupsd[22622]: Power failure.
Aug  7 22:59:32 bitler apcupsd[22622]: Power failure.
Aug  7 22:59:37 bitler apcupsd[22622]: Power failure.
Aug  7 23:59:32 bitler apcupsd[22622]: Power failure.
Aug  8 05:51:10 bitler apcupsd[22622]: Power failure.
Aug  8 05:51:21 bitler apcupsd[22622]: Power failure.
Aug  8 05:51:31 bitler apcupsd[22622]: Power failure.
Aug  8 05:51:35 bitler apcupsd[22622]: Power failure.
Aug  8 06:59:24 bitler apcupsd[22622]: Power failure.
Aug  8 06:59:32 bitler apcupsd[22622]: Power failure.
Aug  8 06:59:36 bitler apcupsd[22622]: Power failure.
Aug  8 11:29:11 bitler apcupsd[22622]: Power failure.
Aug  8 11:29:28 bitler apcupsd[22622]: Power failure.
Aug  8 13:59:17 bitler apcupsd[22622]: Power failure.
Aug  8 13:59:22 bitler apcupsd[22622]: Power failure.
Aug  8 13:59:23 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  8 14:00:19 bitler apcupsd[22622]: Power failure.
Aug  8 18:59:37 bitler apcupsd[22622]: Power failure.
Aug  8 21:27:11 bitler apcupsd[22622]: Power failure.
Aug  8 21:27:16 bitler apcupsd[22622]: Power failure.
Aug  8 21:27:17 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  8 21:27:25 bitler apcupsd[22622]: Power failure.
Aug  8 21:27:39 bitler apcupsd[22622]: Power failure.
Aug  8 21:29:11 bitler apcupsd[22622]: Power failure.
Aug  8 21:29:13 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  8 21:29:22 bitler apcupsd[22622]: Power failure.
Aug  8 21:29:25 bitler apcupsd[22622]: Power failure.
Aug  8 21:29:27 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  8 21:29:37 bitler apcupsd[22622]: Power failure.
Aug  8 21:29:38 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  8 21:30:20 bitler apcupsd[22622]: Power failure.
Aug  8 21:30:22 bitler apcupsd[22622]: Power failure.
Aug  8 21:30:24 bitler apcupsd[22622]: Power failure.
Aug  8 21:30:28 bitler apcupsd[22622]: Power failure.
Aug  8 21:30:29 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  8 21:30:37 bitler apcupsd[22622]: Power failure.
Aug  8 22:39:11 bitler apcupsd[22622]: Power failure.
Aug  8 22:39:25 bitler apcupsd[22622]: Power failure.
Aug  8 22:39:28 bitler apcupsd[22622]: Power failure.
Aug  8 22:59:11 bitler apcupsd[22622]: Power failure.
Aug  8 22:59:18 bitler apcupsd[22622]: Power failure.
Aug  8 22:59:26 bitler apcupsd[22622]: Power failure.
Aug  8 22:59:28 bitler apcupsd[22622]: Power failure.
Aug  8 22:59:40 bitler apcupsd[22622]: Power failure.
Aug  8 23:59:11 bitler apcupsd[22622]: Power failure.
Aug  8 23:59:22 bitler apcupsd[22622]: Power failure.
Aug  8 23:59:24 bitler apcupsd[22622]: Power failure.
Aug  9 05:54:10 bitler apcupsd[22622]: Power failure.
Aug  9 05:54:21 bitler apcupsd[22622]: Power failure.
Aug  9 05:54:22 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  9 05:54:39 bitler apcupsd[22622]: Power failure.
Aug  9 06:59:10 bitler apcupsd[22622]: Power failure.
Aug  9 06:59:17 bitler apcupsd[22622]: Power failure.
Aug  9 06:59:19 bitler kernel: hub 5-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
Aug  9 06:59:27 bitler apcupsd[22622]: Power failure.
Aug  9 06:59:28 bitler apcupsd[22622]: Power failure.
Aug  9 06:59:32 bitler apcupsd[22622]: Power failure.
Aug  9 06:59:36 bitler apcupsd[22622]: Power failure.
Aug  9 06:59:39 bitler apcupsd[22622]: Power failure.
Aug  9 12:59:22 bitler apcupsd[22622]: Power failure.
Aug  9 12:59:23 bitler apcupsd[22622]: Power failure.
Aug  9 12:59:27 bitler apcupsd[22622]: Power failure.
Aug  9 13:59:24 bitler apcupsd[22622]: Power failure.
Aug  9 13:59:28 bitler apcupsd[22622]: Power failure.
Aug  9 13:59:34 bitler apcupsd[22622]: Power failure.

As you can see, all the EMI notices correspond exactly with the UPS switching over to battery; all the EMI notices are 1 or 2 seconds after the power failure notice, without exception. And no, I didn’t just show the EMI notices that suit me; these are all of them.

APC suggested it might have something to do with the 3rd party software (because they don’t support Linux themselves), but that’s ridiculous of course. The software doesn’t have the ability to command the UPS to switch over to battery, so the order of events has to be that the UPS switches and that the USB hub is disrupted by that. This is exactly the order of events the logs show.

I think this problem is common in the CS type of UPS’s and perhaps in other models as well and that just because of the frequent switching it shows more often. I still have to find out whether it’s the proximity of the UPS to the computer or if the EMI is traveling over the USB cable. Putting the UPS about a meter below the machine didn’t help, anyway.

One very big problem with this situation is that I can’t reliably connect a USB hard disk to the system for backups. The filesystem and the data on it will not take kindly to connection interrupts.


    1 Comment ( Add comment / trackback )

    1. (permalink)
      Comment by halfgaar
      On August 9, 2009 at 12:50

      I need to work on the layout of the log. Will do that soon… The table is a bad idea. Edit: done.