 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.
- A large number of tapes implies more waiting time.
- 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 The data volume to be retrieved before issuing a request. It is easy to retrieve Gigabytes of data. Try to retrieve a sensible numbershould be a sensible, up to 20GB per request. You also need to check
 Check that computer resources and limits are adequate for the amount of data to retrieve.They need to estimate the - The number of fields to be retrieved before issuing a request. Try to retrieve should be a sensible number, up to 100.000 fields per request.
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