Can we set a deletion programmed over time, for example delete files older than 6 months in orthanc. If yes what are the parameters to modify?
No. You can however limit the size used or the number of patients:
// Maximum size of the storage in MB (a value of "0" indicates no
// limit on the storage size)
"MaximumStorageSize" : 0,
// Maximum number of patients that can be stored at a given time
// in the storage (a value of "0" indicates no limit on the number
// of patients)
"MaximumPatientCount" : 0,
You can easily implement this logic by scripting the REST API of Orthanc:
http://book.orthanc-server.com/users/rest.html
The solution consists in combining the following two sample Python scripts that are part of the Orthanc source distribution:
https://bitbucket.org/sjodogne/orthanc/src/default/Resources/Samples/Python/DeleteAllStudies.py