As far as I know, ownCloud itself doesn’t provide that functionality on the server side, but it is possible to configure the client to use bandwidth limits. Otherwise you will have to look into a third party solutions, you can find more information here:
Not sure what you mean with “cas”, but I would recommend you install a test server and try out the client on your computer. Once you do that, it’s a pretty self explanatory process guided with a wizard. You can find the client docs here:
I would just run a
du on the user directories in the ownCloud data folder, but this won’t include external mounts and similar. For that you would have to run a query like so on the database:
select m.user_id, concat(convert(fc.size / 1024 / 1024, integer), 'MB') as size from oc_mounts m, oc_filecache fc, oc_storages s where m.mount_point=concat('/', m.user_id, '/') and s.numeric_id=m.storage_id and fc.storage=m.storage_id and fc.path='files' order by fc.size desc;
Otherwise if you require professional ownCloud support or consulting you can contact firstname.lastname@example.org.