--numeric-ids don't map uid/gid values by user/group name
--timeout=TIME set IO timeout in seconds
-I, --ignore-times don't exclude files that match length and time
+ --size-only only use file size when determining if a file should be transferred
-T --temp-dir=DIR create temporary files in directory DIR
--compare-dest=DIR also compare destination files relative to DIR
-z, --compress compress file data