Oracle RMAN Multiplexing


RMAN uses two different types of buffers for I/O: disk and tape. RMAN multiplexing determines how RMAN allocates disk buffers. RMAN multiplexing is the number of files in a backup read simultaneously and then written to the same backup piece. The degree of multiplexing depends on the FILESPERSET parameter of the BACKUP command as well as the MAXOPENFILES parameter of the CONFIGURE CHANNEL or ALLOCATE CHANNEL command.


For example, assume that you back up two data files with one channel. You set FILESPERSET to 3 and MAXOPENFILES to 8. In this case, the number of files in each backup set is 2 (the lesser of FILESPERSET and the files read by each channel) and the level of multiplexing is 2 (the lesser of MAXOPENFILES and the number of files in each backup set).