[glue-wg] Some doubts

[Riccardo Zappi]

Hi Stephen,

Burke, S (Stephen) wrote:
> Riccardo Zappi [mailto:riccardo.zappi at cnaf.infn.it] said:
>> I know only that LHCb prefers the use of FILE 
>> protocol rather than RFIO protocol, or in other words, LHCb 
>> users would 
>> like prevent the use of RFIO protocol even if it is supported.
> 
> I still don't see the problem. Advertising rfio just says that it's
> available, it doesn't force anyone to use it. If lhcb have coded their
> application in a way where it does force them to use it then that is a
> bug in their code.

Yes, I agree with you.
My example doesn't report a real problem, but perhaps only a excessive 
end-user apprehension caused by some bad past experience or by something 
else.

I can imagine jobs written to make use of an external libraries to 
interact with IS and SRM. That libraries could retrieve the _unordered_ 
set of supported protocols from IS. The result set contains all the 
protocols supported by the Storage Service. Then the library builds the 
SRM request using the _unordered_ protocol list returned by IS query.

Therefore, in theory, RFIO could be before to FILE protocol because a 
specific order is not guaranteed by IS.

If my speculation is correct, then the solutions could be:

1) Modify external library used by jobs adding the possibility to 
specify the order in protocol preferences.

  or/and

2) make possible to specify which protocols are available for each 
"StorageShare"

I think that both solutions could be implemented.

But, if you think solution 2) inopportune, it is the same. We can 
suggest strongest tests on services providing the protocols to make end 
users less worried.

Bye,
Riccardo






> 
> Stephen


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Riccardo Zappi

Istituto Nazionale di Fisica Nucleare - CNAF
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e-mail: riccardo.zappi at cnaf.infn.it
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