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What is the objective of these pages?

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To help users to improve their MARS requests performance via the WebAPI. 

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A good understanding of the MARS efficiency issues is essential especially for users that are interested in downloading large amounts of data.

What would be the natural way to group requests?

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  • The idea is to request as much data as possible from the same tape file or to reduce the number of tapes involved.
  • The number of tapes a MARS request is going to access will have an impact on its scheduling on the server. As a rule of thumb, two or more separate requests accessing files on different tapes are scheduled more efficiently than a single request accessing two or more tapes. A large number of tapes implies more waiting time.

  • Additionally users should be aware of the following:

    • They need to estimate the data volume to be retrieved before issuing a request. It is easy to retrieve Gigabytes of data. Check that computer resources and limits are adequate for the amount of data to retrieve.
    • They need to estimate the number of fields to be retrieved before issuing a request. Try to retrieve a sensible number, up to .

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