SRR for storage topology description

513-1-11 (CERN)



Meeting to discuss the evolution of the WLCG Information System


Alessandro, Oliver, Fabrizio, Andrea, Paul, Andreas, Dimitrios, Julia

Julia walked through the CRIC simplified schema for the storage service


Since schema foresees a single logical storage service per  VO, whether DB records for protocols would be replicated in case the same protocol is used by several VOs.


For CRIC internal implementation this is true. However, JSON structure itself does not completely reproduce CRIC schema, it just needs to contain all necessary info in order to properly inject data into CRIC. In json structure the replication of the service block per VO  is not foreseen. If the same storage service is shared by several VOs, there is only one service description block in JSON. On the other hand every storageshare block contains the list of VOs which are using this particular share. Every protocol endpoint (storageendpoint) contains the list of shares on a particular storage it can serve, in most cases the value of this attribute is 'all'. See Prague example for multi-VO storage description.

Then followed long discussion regarding CRIC concepts of capability vs activity. In short capability is protocol property known and defined by storage/site admin, while activity is a possibility to overload/extend (by more details) by the experiment capability defined by storage/site admin. These two concepts are not yet described in the proposed structure of the json file, we might come to it later after gaining more experience.

Julia asked storage providers about possible time line for SRR implementation.

DPM is done going to the deployment phase

EOS is prototyped at CERN, however needs more work before deployment to other sites. Julia, Andreas and Dimitrios will discuss offline.

dCache Paul confirmed that he can work on it starting mid October and might have something for test and validation by the 1st of November. He asked for json validation script, Dimitrios will provide it before mid October.

STORM Andrea asked what is the difference between topology JSON and accounting JSON. Julia and Alessandro explained that it is almost the same thing. Accounting json is an extension of the topology one with accounting numbers and time stamps of measurement.  Andrea told that then there was already implementation for ATLAS endpoint at CNAF.

Julia told that CRIC and storage space accounting developers were looking forward to get an URL they can consume and therefore validate the structure and content. Andrea will send an URL soon.

XROOT Wei did not join, Julia will ping him.

There was a short  discussion how the progress should be followed up. Julia told that we needed to checkpoint the progress which can be done either at DOMA meetings (convenient since all experts are normally present) or at the dedicated monthly meetings.

Alessandro asked all storage experts to check again JSON structure and to provide their feedback. They can provide their feedback to the SRR googledoc:











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