ensure files does not exeed OXICLOUD_MAX_UPLOAD_SIZE, prefer to deny from header rather consuming bandwidth
add OXICLOUD_DIRECT_PUT_MAX_BYTES for direct PUT (non chunked), admins can fine tune their prefered values
explain OXICLOUD_CHUNK_DIR and OXICLOUD_UPLOAD_TMPDIR
and also the OXICLOUD_CHUNK_MAX_BYTES & OXICLOUD_UPLOAD_TMPDIR
to help administratorrs to defined correctly their storage architecture