[glue-wg] Some doubts

[Riccardo Zappi]

Hi Stephen,

Burke, S (Stephen) wrote:
> Sergio Andreozzi [mailto:sergio.andreozzi at cnaf.infn.it] said:
>   > in the current modeling, it cannot be implied because 
>> storageResource is 
>> associated to a dataStore via a many-to-many relationship.
>>
>> It would have been possible in this case: storageResource 
>> 1--* dataStore
> 
> That seems to be a mistake, Datastore to Resource should indeed be many
> to 1. I don't think it could make sense for one piece of hardware to be
> managed by multiple systems.

I'm not sure about this.
Within a storage area networks you can find several servers sharing 
storage devices such as disk subsystem and tape libraries and also data 
stored upon them. SAN aggregate and share the storage devices via volume 
manager. You can deploy some different file systems upon the same SAN 
infrastructure.

I imagine a cluster file system, like GPFS, managing the disk system and 
TSM managing the mass storage system. Both systems are using the same 
SAN. Moreover, the storage administrator could build several file 
systems using GPFS, for example one per supported VO.

Now, if I've understood well, there are only two/three DataStores:
- one to represents the "disk quality",
- one to represents the "tape quality",
- and, eventually, one to represents the "hierarchical-system" not 
manageable by user.

But, at the same time, we have a set of StorageResources corresponding 
to File Systems created..

Is it correct above description?

If yes, I cannot be able to assign Size properties to DataStores.. vice 
versa I can assign sizes to StorageResources.

If no, I don't understand what DataStore is.

We could move Size properties to StorageResources and make a 
relationship between StorageShare <-> StorageResource and between 
StorageResource <-> DataStore (many-to-many). In this way we can 
represents above example, I think.

I don't know about the relationship between StorageShare and DataStore. 
Perhaps it is still needed.

> 
> Stephen

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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