[Engine-devel] [Design for 3.2 RFE] Host Power Management Multiple Agent Support
Eli Mesika
emesika at redhat.com
Sat Nov 17 21:14:13 UTC 2012
----- Original Message -----
> From: "Lon Hohberger" <lhh at redhat.com>
> To: "Itamar Heim" <iheim at redhat.com>
> Cc: "Eli Mesika" <emesika at redhat.com>, "engine-devel" <engine-devel at ovirt.org>
> Sent: Friday, November 16, 2012 7:42:12 PM
> Subject: Re: [Engine-devel] [Design for 3.2 RFE] Host Power Management Multiple Agent Support
>
> On 11/16/2012 11:35 AM, Itamar Heim wrote:
> > On 11/16/2012 03:06 AM, Eli Mesika wrote:
> >>
> >> Requirements:
> >> http://wiki.ovirt.org/wiki/Features/HostPMMultipleAgents
> >> DR :
> >> http://wiki.ovirt.org/wiki/Features/Design/DetailedHostPMMultipleAgents
> >> _______________________________________________
> >> Engine-devel mailing list
> >> Engine-devel at ovirt.org
> >> http://lists.ovirt.org/mailman/listinfo/engine-devel
> >>
> >
> > Lon - thoughts on this?
> >
>
>
> Looks the first thing that jumps out is that it looks like you can
> have:
>
> - do this one off action && do this one off action
> - do this one off action || do this one off action
>
> So, try device A, and if this fails, try device B - or, if it's
> really
> two ports on device A (but two calls), both must succeed.
>
> One thing I wonder is whether these use cases are covered.
>
> 1) With WTI units and similar, many have two independent power rails.
> This means that if someone trips over one of the power cables going
> to
> the power switch unit, the host will still have power.
>
> A || (B && B')
> ^ ^ ^
> | +----+---- WTI dual-rail remote power switch
> | (two ports used - one on each power rail)
> |
> +--------------- iLO / IPMI / etc.
>
> 2) More common with the smaller APC units is that most have a single
> power supply rail. For power redundancy, it's not recommended to
> ever
> plug both power supplies in to the same single-rail APC unit.
>
> A || (B && C)
> ^ ^ ^
> | | +---- APC device 2 port 1
> | +--------- APC device 1 port 1
> +--------------- iLO / IPMI / etc.
>
> E.g. try the iLO device first, but if that fails, you need to cut off
> both power supplies (then on). This is presumably less harsh to the
> machines. I also would not /necessarily/ limit things to two power
> supplies, but I think two power supplies is the 99% use case.
>
> I'll keep looking.
Thanks Lon
I had added those questions in the Feature Talk page : http://wiki.ovirt.org/wiki/Talk:HostPMMultipleAgents
I will discuss those cases with Simon tomorrow and try to answer those questions
>
> -- Lon
>
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