If this integer parameter is set to a non-zero value, Samba will write to files asynchronously when the request size is bigger than this value. Note that it happens only for non-chained and non-chaining reads and when not using write cache. The only reasonable values for this parameter are 0 (no async I/O) and 1 (always do async I/O). Compared to this parameter has a smaller effect, most writes should end up in the file system cache. Writes that require space allocation might benefit most from going asynchronous. write cache size aio read size 1 0Always do writes synchronously