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Re: [Condor-users] about multiple scheduler issues

Hi Erik,

Thanks very much for your clear explanation.

You are right, I am actually asking if it is possible to have more than
one negotiators with multiple schedulers. Since I think that case is
possible to exist in condor-g environment.

and I think you have answered my questions. Really thanks a lot.


I have more understanding about the condor and condor-g

> On Sat, Feb 19, 2005 at 04:40:24PM +0800, Carson Hung wrote:
>> Hi,
>> Since it is possible to have more than one schedulers/submittors in
>> the clusters.
>> So I would like to know if it is possible that 2 or more schedulers
>> match the same resource to the different jobs if they come from
>> different schedulers/submittors.
> I think you really mean "if it is possible that 2 or more negotiators
> match the same resources to different jobs if they come from different
> schedds" - you can't use the term 'scheduler' twice :)
> In Condor, it's not really possible for the negotiator to match a
> resource twice, because:
> A. There's only one negotiator, so it will only match a resource once
> per neogotiaition cycle.
> B. It is possible for a resource to be matched twice - if it gets
> matched in one negotiation cycle, but doesn't update the collector
> before the next  negotiation cycle starts. We prevent this from
> happening in two ways:
>    1. The negotiation CANNOT start until at least 20 seconds have passed
> since the last one. That usually is good enough.
>    2. The startd can detect if it's been matched twice, and can recover,
> if the 20 seconds wasn't good enough.
> In Condor-G, because there is no claiming (ie the resource doesn't
> automatically tell the collector that it is no longer able to be
> matched), matching twice is more of a problem. We ususally build-in some
> sort of  claiming when we've deployed matchmaking in the past (see the
> USCMS writeup I pointed you at eariler).
> If you advertise your resource to more than one collector/negotiator,
> then matching twice is a real problem. In regular condor, it's not
> possible for a startd to report to two different collectors, so it's not
> a problem.
> -Erik
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