Where can I find a mib for AP7832 metered rack PDU ?

[bbiandov_apc]

Hi everyone,

Where can I find a mib for AP7832 metered rack PDU ?

I looked at the downloads but all I see if firmware, no mib ?

Thanks

[BillP]

Hi,

All of the APC products, except NetBotz, use the PowerNet MIB. You can find that here http://www.apc.com/us/en/tools/download/ and select Filter by Software/Firmware - MIB. Refer to PowerNet MIB v4.1.7 that is the latest version currently available.

[bbiandov_apc]

Thanks Angela, I was looking at the wrong place. Got the PowerNet

I do have a follow up question. I am observing something strange when I do repeated reads of an object. Two out of 10 times the values are credible but for the rest of the read attempts I get return 0 as value?

Is the snmp engine  rate-limited for pulls on those PDUs? What's the minimum time between reads in order to obtain credible value?

If I space the reads 30 seconds apart I get reliable 100% credible value all the time so I figured there must be some rate limiting mechanism built-in.

BWT we are dealing with AP7832 PDU rack with the latest firmware v3.7.4 of 11/14/2007

Thank you

~B

[BillP]

How often were you reading to start? Here is some information I have below to keep in mind:

The AP78XX and AP79XX Rack PDUs take approximately 1.5 seconds for each current measurement reading. In addition, every 50 times through the current measurement loop, the power supplies voltages are checked. The power supplies take an additional 1.5 seconds for each measurement, for a total of three seconds. Therefore, for a phase monitored unit, the typical time to read all the phases would be 3 x 1.5 seconds = 4.5 seconds. Every 50th cycle, an additional three seconds would need to be added to account for the power supply measurement, for a total of 7.5 seconds. For a more complex device that has bank or outlet monitoring, like the AP7856 which has six outlet banks, it would take (3 + 6) x (1.5) = 13.5 seconds to measure all the phases and all the banks. Then every 50th cycle, this would increase to 13.5 seconds + 3 seconds = 16.5 seconds.

This covers how the data log on board the PDU is populated so SNMP will work similarly. The PDU has two banks from what I can tell. I imagine your experience will also differ on what other things the PDU is doing and how often measurements change. The PDU uses a real time OS so if you have like every other service running and also if you're using more CPU intensive things like SNMPv3, HTTPS, SSH, etc, you may see behavior like you described.

I would say most customers do once a minute at the high frequency but 30 seconds you said works OK and sounds reasonable to me. Sorry I don't have more specifics but beyond the above, we don't have a specification documented I could find.

[bbiandov_apc · Accepted solution]

Hi Angela,

Thanks for your reply. I was reading an object every 3 seconds for about 10 times. That's NOT concurrently but sequentially with a 3 seconds pause in between. My issue is NOT about the internals of the PDU and how often "it" gathers the data internally from the ADC or what not. My issue is that if I do 10 reads spaced 3 seconds apart only 3 of those get real data and the rest get ZERO as a value of the object. 

For example if I read the current Volts 10 times, 3 seconds apart I get three readings with 132v which is pretty much expected but the rest of the readings I get 0v which I know isn't accurate.

That's what I've observed and hence my question about some kind of rate limiter on the 7832 network hardware? 

As a test I did the same against an AP9631 UPS device and I do NOT have the same problem!

Thanks

~B