[Engine-devel] [Design for 3.2 RFE] Host Power Management Multiple Agent Support

[Eli Mesika]

----- 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
>