Is it possible to lower the cache and actually write to the disk more often?

A big file is being uploaded to my server. Console is reporting 66 GB of this file uploaded so far but Explorer is showing only half that size, 31 GB. Modify date is showing yesterday even though the upload has been going all night. Is it possible to lower the cache and actually write to the disk more often? This server has only 8 GB of RAM so the file must be cached on disk somewhere but I would prefer to actually write to the desired destination.