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by Marie Anne Bizouard last modified 2012-04-26 22:08

VDAS call


  1. NSF 4 upgrade @ Cascina (Livio)
  2. Computing model draft - commissioning needs
  • disk storage capacity / circular buffer
  • Virgo data storage and access latency
  • Data access from the online farm: requirements
  • Special needs (services?, hardware?)
  • Network changes (online vs offline)?
  • ...


Loic, Didier, Benoit, Stefano, Livio, Alberto, Cristiano, Frederique, Elena, Franco, Salvatore, Nicolas, MAB [Minutes]. Antonella

1. NSF4 test:

Stefano: test of configuration of client of NSF version 4 needed to mount disk on the SL6.2.

2. Computing model:

About Virgo data storage: increase of the storage capacity (410 TB), but no big change needed of how to write and access data. Mainly software improvement: for instance we should avoid to wait for the end of the writing of the end of the file (2-3 mns). Possible solution : write short trend files in parallel to the long files. Few mns latency could be reduced.

Didier: faster access to trend data with temporary files--> DAQ optimization.

Conclusion: mostly software improvement

Stefano: big files available few mns latency. Circular buffer of a few mns. Fast data access buffer. Stol2. Few mns of data. Small amount of data ~5GB.

Didier: bandwidth access?

Benoit: can't ask to be able to read the rawdata files much faster than the real data acquisition rate.

MAB: NoEMi foresees to analyze up to 200 channels in parallel. Whatever the solution found (data broadcasting, local copy of the channels on disk, increase of the network bandwidth, ....) it is important for applications like NoEMi to define the high level requirements (latency, nb of channels, ...). Current implementation could be improved.

Conclusion : need to clarify how many users/process will access rawdata files on disk. Need to specify that projects identified as high priority will have to be able to access rawdata files at Cascina. Apart these projects, what is considered is a few users's applications (dataDisplay like). 

Stefano reminds that a "normal" upgrade of the network, and the storage farm will be upgraded anyway. The current network architecture alows anyway to choose a general setup that can be deployed according to the needs.

Services : databases is one of the services that have been identified. For the moment specific requirements are not given. Will have to define this in the future.

Missing information in the document: back up data / data integrity. Benoit mentions remote back up solution. Need more information. Livio will provide information on how the back up is done at Cascina. MAB reminds that Virgo data backup in CC is done by having a copy at CNAF and a copy at CCIN2P3.



- will need to discuss NoEMi requirements in another meeting

- databases

- back up

- all specific requirements must be better defined to help the design of the computing upgardes at cascina