Burke, S (Stephen) ha scritto:

>LHC Computer Grid - Rollout 
>  
>
>>[mailto:[log in to unmask]] On Behalf Of Charles Loomis
>>    
>>
>said:
>  
>
>>>1) Keep the current syntax, allow matching against multiple 
>>>      
>>>
>>subclusters,
>>    
>>
>>>and pass the subcluster name to the batch system.
>>>      
>>>
>>This is not a solution to the problem.
>>    
>>
>
>It's a solution to part of the problem, i.e. that currently jobs may
>avoid sites even if only 1 WN out of 500 doesn't match the requirement,
>because you have to publish the most restrictive limit.
>
>  
>
>>I would instead opt for a hybrid approach of 2) and 3).  
>>Allow people to 
>>define parameters like in 3) and have whatever processes the 
>>final JDL 
>>combine those with any explicit requirements to arrive at the full 
>>expression.  Only those limits given separately would be 
>>passed to the local batch system.
>>    
>>
>
>Yes, that doesn't sound too bad - but in itself it wouldn't solve the
>above problem, so you might still want to think about doing subclusters
>properly, or else changing the glue schema to go back to max/min values.
>
>Stephen
> 
>  
>

Hi,
my idea was more or less the option 3) proposed by Stephen. But, as he 
said, this doesn't solve the underusage problem created by having the 
min values published in the GRIS. Anyway, if we go with a max/min 
schema, or if we publish only max values, we have to face another 
problem: how do we handle jobs dispatched to a CE when there are no free 
nodes matching the requirements (e.g. because they are busy)?
The CE could reject it and the WMS retry mechanism would submit it 
somewhere else, but this sounds very inefficient.
Another solution would be that the CE keeps the job queued until a 
suitable node is free, but this would kill any hope for the WMS to make 
any intelligent decision, as this additional queueing time would not be 
visible in the glue schema.
A third option could be the implementation of a direct WMS <-> CE 
negotiation before the actual job submission. This would require some 
completely new code on both WMS and CE, and would be even heavier than 
the simple check with the CE GRIS which LCG wanted removed from the 
brokers...

Sorry if you already discussed this problem, I've tried to read all the 
messages in the thread but I could still have missed something...

Cheers,
David

-- 
David Rebatto
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