Queries in phosphor-pid-control(swampd)

[Kumar Thangavel]

Classification: Internal

Hi Patrick,

          Thanks for your response.  

          Our requirement is when all fan fails in the system, the slots should be 12 V Power off.  I will send the separate mail for this in detail.

Thanks,
Kumar.

-----Original Message-----
From: Patrick Venture <venture at google.com> 
Sent: Wednesday, November 11, 2020 8:34 PM
To: Kumar Thangavel <thangavel.k at hcl.com>
Cc: openbmc at lists.ozlabs.org; Josh Lehan <krellan at google.com>; Velumani T-ERS,HCLTech <velumanit at hcl.com>; Vijay Khemka <vijaykhemka at fb.com>; Patrick Williams <patrickw3 at fb.com>; sdasari at fb.com
Subject: Re: Queries in phosphor-pid-control(swampd)

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On Thu, Nov 5, 2020 at 4:22 AM Kumar Thangavel <thangavel.k at hcl.com> wrote:
>
> Classification: Internal
>
> Hi All,
>
>
>
>       Does the current phosphor-pid-control handled the fan failures or if fan values is 0 ?  Looks like, it ignores the fan values is 0 case.
>
>       Could you please clarify me, how the fan(single/both) failures handled. if both fan failures, Do we need to power off the chassis or need to do power sled cycle ?

The answers to the failure behaviors you wish are outside the scope of controlling the fans themselves.  As I understand it, it's up to you or your use case what happens when fails start failing. The pid control daemon has default fail-safe values you can set, as well as minimum RPM set-points, so that if some things fail, it'll still move forward operating in a best effort to cool the system.  But with fans failing, if there's something more one wishes to do with it, my recommendation would be to reach out with a broader email subject line
-- there may be something already in openbmc (probably is) that'll track failures and trigger behaviors.

However, currently pid control doesn't "manage the system."  Which it sounds like you want.  Or not?  Your question sounds like you're not sure what the system _should_ do in a fan failure case, to which I cannot reply.

Thanks!

>
>
>
> Thanks,
>
> Kumar.
>
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