Solution : https://service.sap.com/sap/support/notes/1474270 (SAP Service marketplace login required)
Key words : 
sap tools sapup/sapehpi/sum, junction mountpoint autogrow mssspace, handle windows junctions correctly, error> insufficient free space, <yyy> mb                   ---> calculated freespace, file system level incorrectly, database space check routines, sap systems running, file system configurations, face error messages
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