[glue-wg] Some doubts

[Riccardo Zappi]

Hi Maarten,
thanks for your comments.

Maarten Litmaath wrote:
> Sergio Andreozzi wrote:
> 
>>> You are right about the complicated scenario of supported protocol. I 
>>> do not know if the use of the AccessPolicy on protocol works. Suppose 
>>> the scenario where LHCb wants RFIO protocol available for one 
>>> StorageShare, while for another one LHCb wants only FILE protocol. 
>>> How can we represent this situation with ACL?
>>>  
>>
>>
>> we might want to add the association from AccessProtocol to StorageShare;
>> what do people think about this?
> 
> I suppose it would be OK (just a few foreign keys in the Share),
> but I think Riccardo's use case is _not_ a good example: CNAF is just
> being asked to do something silly to work around an LHCb software bug!
> 
Maarten, you are right. My example is not a good example.

Let me try to explain better. I made some inaccuracies in my description 
and so misunderstanding was born. I do not know if there exists a LHCb 
software bug... maybe not. 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 tried to explain the case of a StorageService serving two or more 
StorageShares belonging to different VOs with divergent "preferences" 
about supported protocols, and I've reported a real use case about this.

>>>> is is exactly the role of the Resource - maybe the name isn't very
>>>> good but the Resource is supposed to represent the management software.
>>>> So you would have a Resource for GPFS, with an associated Datastore to
>>>> represent the disk servers.
>>>>
>>>>    
>>>
>>> In this case, we could define the StorageShare on StorageResource.. 
>>> or not?
>>>  
>>
>>
>> also here... I think Riccardo is right. The association from 
>> StorageShare to DataStore should be changed from StorageShare to 
>> StorageResource...
> 
> No, one reason we invented the DataStore was to show explicitly what
> hardware is being used by a Share, so we need to keep that relationship.
> 
>> alternatively, we can add in parallel if people really want to 
>> discover the type of data store on which a storage share is configured.
>> This will complicate the life of sysadmin who have to configure the 
>> providers, therefore, let us consider this issue carefully.
> 
> I would argue in the other direction: the Share-Resource relation can be
> inferred (if desired) from the Share-DataStore relation, but not vice 
> versa.

I need to think more about DataStore. I'm still not completely aware of 
DataStore, StorageResource and StorageShare relationship.

Bye,
Riccardo


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Riccardo Zappi

Istituto Nazionale di Fisica Nucleare - CNAF
Viale Berti Pichat, 6/2,  40127 BOLOGNA - ITALY
Phone:  +39-051-609-2868                Fax:    +39-051-609-2746
e-mail: riccardo.zappi at cnaf.infn.it
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