Subject: [eman] power inlets

From: Juergen Quittek <[email-masked]>
Date: Fri, 15 Apr 2011 19:05:52 +0200

Dear all,

We are currently revising the eman requirements and discussing how to cover  devices with multiple power supplies. 

A typical case is a server with dual main power supply. Often such servers have their two power inlets connected to different power distribution trees in order to be able to continue operation even when power fails in one power distribution tree. Typically, servers do not just have two inlets, but two full built-in power supply units. If one breaks, the other can take over.

I have thought about how to cover such servers in the requrements. My current solution starts with the point that a powered device may have more than one power inlet. Then the eman standard to be developed must provide means (managed objects in MIB modules) for monitoring each power inlet individually. This concerns monitoring of instantaneous power, consumed energy, power quality, and maybe even just availability of power at an inlet.

Does anyone think this is a reasonable way to go? The inlet concept somehow blurs the role of built-in power supply units.

Do we have better alternatives?

Thanks,

    Juergen

---

From: "John Parello (jparello)" <[email-masked]>
Date: Fri, 15 Apr 2011 11:10:29 -0700

HI Jeurgen,

This same pattern comes into play for PoE devices as well. You may have
a PoE device that requires say 30 W of power and connects to two 15 W
interfaces in order to power it.

In our implementations of energy monitoring we simple maintain a
relationship vector called "poweredby" that contains the ids of the
devices. We also have a similar vector field called "meteredby" 

Then if each managed object has power, energy and demand tracking the
accounting can be taken care of in the management stations.

Jp

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Juergen Quittek
Sent: Friday, April 15, 2011 10:06 AM
To: [email-masked] list
Subject: [eman] power inlets

Dear all,

We are currently revising the eman requirements and discussing how to
cover  devices with multiple power supplies. 

A typical case is a server with dual main power supply. Often such
servers have their two power inlets connected to different power
distribution trees in order to be able to continue operation even when
power fails in one power distribution tree. Typically, servers do not
just have two inlets, but two full built-in power supply units. If one
breaks, the other can take over.

I have thought about how to cover such servers in the requrements. My
current solution starts with the point that a powered device may have
more than one power inlet. Then the eman standard to be developed must
provide means (managed objects in MIB modules) for monitoring each power
inlet individually. This concerns monitoring of instantaneous power,
consumed energy, power quality, and maybe even just availability of
power at an inlet.

Does anyone think this is a reasonable way to go? The inlet concept
somehow blurs the role of built-in power supply units.

Thanks,

    Juergen
_______________________________________________
eman mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/eman

---

From: Juergen Quittek <[email-masked]>
Date: Fri, 15 Apr 2011 21:12:03 +0200

---

From: Juergen Quittek <[email-masked]>
Date: Fri, 15 Apr 2011 21:20:59 +0200

Hi Paul, 

I am sorry for spamming with the empty email that I just sent. Touchscreens are dangerous ...

Please see a question inline.

> accounting can be taken care of in the management stations.

Just for my understanding: i have an idea what power and energy are. But what so you refer to with "demand"?

Tanks,

   Juergen

---

From: "John Parello (jparello)" <[email-masked]>
Date: Fri, 15 Apr 2011 13:25:27 -0700

Hi Juergen,

Demand is and average rate of energy consumed per interval of time. 

This is the measurement utilities (most US,EU not China etc) use to
charge. They typically charge for the highest demand interval over a
period. This recognized that devices may spike in power at moments but
the charges are for the peak demand

This is also the term used in systems that negotiation systems (Demand
Response systems)  with providers. They are negotiating the demand they
require for a period (Ex: OpenADR)

There's a description and graph for clarity so that people understand
the terms (which get over loaded in the vernacular) in the EMAN preso
here:

http://tools.ietf.org/agenda/80/slides/eman-1.pdf

For others that may want a simple clarification of power, energy and
demand simply put here:

  Power is like a reading off a speedometer
  Energy is like a reading off an odometer
  Demand would be like a "trip" odometer reading divided by time and
collected at set intervals. 

In our monitoring MIB draft we placed energy and demand in the same
object and made it optional but in this problem space they are best
separated since they are distinct and used for different mgt purposes.

HTH
Jp

-----Original Message-----
From: Juergen Quittek [mailto:[email-masked]] 
Sent: Friday, April 15, 2011 12:21 PM
To: John Parello (jparello)
Cc: <[email-masked]>
Subject: Re: [eman] power inlets

Hi Paul, 

I am sorry for spamming with the empty email that I just sent.
Touchscreens are dangerous ...

> accounting can be taken care of in the management stations.

Just for my understanding: i have an idea what power and energy are. But
what so you refer to with "demand"?

Tanks,

   Juergen

---

From: Brad Schoening <[email-masked]>
Date: Fri, 15 Apr 2011 21:02:16 +0000

Hi Juergen,

I would definitely take a look at the UPS-MIB which models this with input groups.

UpsInputEntry ::= SEQUENCE {
      upsInputLineIndex   PositiveInteger,
      upsInputFrequency   NonNegativeInteger,
      upsInputVoltage     NonNegativeInteger,
      upsInputCurrent     NonNegativeInteger,
      upsInputTruePower   NonNegativeInteger
  }

upsOutputSource OBJECT-TYPE
      SYNTAX     INTEGER {
          other(1),
          none(2),
          normal(3),
          bypass(4),
          battery(5),
          booster(6),
          reducer(7)
      }

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Juergen Quittek
Sent: Friday, April 15, 2011 1:06 PM
To: [email-masked] list
Subject: [eman] power inlets

Dear all,

Thanks,

    Juergen

---

From: Juergen Quittek <[email-masked]>
Date: Fri, 15 Apr 2011 23:38:30 +0200

Hi Brad,

Thanks for the hint. I had looked at the UPS MIB. The problen is that the snippet you cited is almost all that is in there. For each listed object there is just half a line of description :-(

    Jürgen

---

From: Bruce Nordman <[email-masked]>
Date: Fri, 15 Apr 2011 16:03:46 -0700

I can see two cases - when both power supplies are in the same electricity
domain, and when they are not.  If we only had the second case, then the
two reports on the device would have the same UUID, but different domains,
so a NMS would know they are different power supplies.  However, since
they could be in the same domain, then some labeling of the supplies is
needed.  I haven't looked at the MIB to see if there is an obvious existing
variable to do this with, but otherwise just a numeric counter (usually just
always "1") could do this.  This would be used in both cases (same domain
and different domain).  This variable not being present would also imply
just one supply.

For reporting, if reported by a device other than the server (or whatever
the
end device is), then it would just report two separate entries with the same
UUID - or more likely, each value would be reported by a different entity.
If the server was reporting on itself, then it would need to specify that it
was reporting on a collection of devices (like an aggregator) rather than
an individual device, so we could reuse that same mechanism, not need
to create a new one.

The meter and power source data would be different for each supply.
Each would report on power state, though the values reported should
be identical.

So, from the perspective of the MIB, there are two separate devices,
though an NMS could observe they are the same device (having the
same UUID) if it wanted to.

So, I think the dual supply case can be accommodated without much
difficulty in our current model.

--Bruce

On Fri, Apr 15, 2011 at 10:05 AM, Juergen Quittek <[email-masked]> wrote:

> A typical case is a server with dual main power supply. Often such servers
> have their two power inlets connected to different power distribution trees
> in order to be able to continue operation even when power fails in one power
> distribution tree. Typically, servers do not just have two inlets, but two
> full built-in power supply units. If one breaks, the other can take over.
>
> current solution starts with the point that a powered device may have more
> than one power inlet. Then the eman standard to be developed must provide
> means (managed objects in MIB modules) for monitoring each power inlet
> individually. This concerns monitoring of instantaneous power, consumed
> energy, power quality, and maybe even just availability of power at an
> inlet.
>
> Does anyone think this is a reasonable way to go? The inlet concept somehow
> blurs the role of built-in power supply units.
>

-- 
*Bruce Nordman*
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman
[email-masked]
510-486-7089
m: 510-501-7943

---

From: Brad Schoening <[email-masked]>
Date: Sat, 16 Apr 2011 16:32:19 +0000

Bruce,

In the UPS MIB, the variable that identifies the supply line are 'upsInputLineIndex' and 'upsOutputLineIndex'.  It would probably be good to review our goals with someone who has worked on the UPS mib and benefit from their implementation experience with power supplies.

Regards,

Brad

From: [email-masked] [mailto:[email-masked]] On Behalf Of Bruce Nordman
Sent: Friday, April 15, 2011 7:04 PM
To: Juergen Quittek
Cc: [email-masked] list
Subject: Re: [eman] power inlets

For reporting, if reported by a device other than the server (or whatever the

--Bruce
On Fri, Apr 15, 2011 at 10:05 AM, Juergen Quittek <[email-masked]<mailto:[email-masked]>> wrote:
Dear all,

Thanks,

   Juergen
_______________________________________________
eman mailing list
[email-masked]<mailto:[email-masked]>
https://www.ietf.org/mailman/listinfo/eman

--
Bruce Nordman
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman<http://eetd.lbl.gov/ea/nordman>
[email-masked]
510-486-7089
m: 510-501-7943

---

From: Benoit Claise <[email-masked]>
Date: Wed, 27 Apr 2011 08:50:48 +0200

Juergen,

Thinking some more about this term "inlet", I believe that we should use 
the term “power source” in the requirement draft as it’s more generic to 
the pattern versus the implementation (inlet) on specific devices. The 
inlet can be used some use cases

Use Case X: Device with Multiple power Sources
In this use case a device is powered by 1..N power sources….etc
Examples:
PoE Device connected to two interfaces from two sources
A PC with two power inlets plugged into two wall outlets
A washing machine bank requiring 240V wired to two 120V sources

Regards, Benoit.