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Hi, Devananda,
Thanks for your reply.
I totally agree with your thought, nova-compute could gathering such information locally. And I think IPMI, using in-band connection, might be more suitable to be used to collect these sensor data.
At the beginning, I thought it would better to put all IPMI part together in Ironic while there is part of code over there.  Now, it looks like that  I thought too much:).

In all, power and temperature could be collected by IPMI locally in nova-compute.


Best wishes
--fengqian
From: Devananda van der Veen [mailto:devananda.vdv at gmail.com]
Sent: Friday, December 20, 2013 3:42 AM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [Nova] [Ironic] Get power and temperature via IPMI

On Wed, Dec 18, 2013 at 7:16 PM, Gao, Fengqian <fengqian.gao at intel.com<mailto:fengqian.gao at intel.com>> wrote:
Hi, Devananda,
I agree with you that new features should be towards Ironic.
As you asked why use Ironic instead of lm-sensors, actually I just want to use IPMI instead of lm-sensors. I think it is reasonable to put the IPMI part into Ironic and we already did:).

To get the sensors' information, I think IPMI is much more powerful than lm-sensors.
Firstly, IPMI is flexible.  Generally speaking, it provides two kinds of connections, in-bind and out-of-band.
Out-of-band connection allows us to get sensors' status even without OS and CPU.
In-band connection is quite similar to lm-sensors, It needs the OS kernel to get sensor data.
Secondly,  IPMI can gather more sensors' information that lm-sensors and it is easy to use. From my own experience, using IPMI can get all the sensor information that lm-sensors could get, such as temperature/voltage/fan. Besides that, IPMI can get power data and some OEM specific sensor data.
Thirdly, I think IPMI is a common spec for most of OEMs.  And most of servers are integrated with IPMI interface.

As you sais, nova-compute is already supplying information to the scheduler and power/temperature should be gathered locally.  IPMI can be used locally, the in-band connection. And there is a lot of open source library, such as OpenIPMI, FreeIPMI, which provide the interfaces to OS, just like lm-sensors.
So, I prefer to use IPMI than lm-sensors. Please leave your comments if you disagree:).


I see nothing wrong with nova-compute gathering such information locally. Whether you use lm-sensors or in-band IPMI is an implementation detail of how nova-compute would gather the information.

However, I don't see how this has anything to do with Ironic or the nova-baremetal driver. These would gather information remotely (using out-of-band IPMI) for hardware controlled and deployed by these services. In most cases, nova-compute is not deployed by nova-compute (exception: if you're running TripleO).

Hope that helps,
-Deva
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