What is the multiplexing level in the preceding backup process?

View the Exhibit and examine the output.
You execute the following RMAN command to perform the backup operation:
RMAN> RUN {
ALLOCATE CHANNEL c1 DEVICE TYPE disk MAXOPENFILES 8;
BACKUP DATABASE FILESPERSET 4;
}
What is the multiplexing level in the preceding backup process?

A.
4

B.
8

C.
7

D.
0

Explanation:
how many datafiles RMAN can read from simultaneously. The basic multiplexing algorithm is as
follows:
– Number of files in each backup set
This number is the minimum of the FILESPERSET setting and the number of files read by each

channel. The FILESPERSET default is 64.
– The level of multiplexing
This is the number of input files simultaneously read and then written into the same backup piece.
The level of multiplexing is the minimum of MAXOPENFILES and the number of files in each
backup set. The MAXOPENFILES default is 8. Suppose that you back up 12 datafiles with one
channel when FILEPERSET is set to 4. The level of multiplexing is the lesser of this number and
8. Thus, the channel simultaneously writes blocks from 4 datafiles into each backup piece. Now
suppose that you back up 50 datafiles with one channel. The number of files in each backup set is
50. The level of multiplexing is the lesser of this number and 8. Thus, the channel simultaneously
writes blocks from 8 datafiles into each backup piece.
http://www.filibeto.org/sun/lib/nonsun/oracle/11.1.0.6.0/B28359_01_200708/backup.111/b28270/rc
mtunin.htm Tuning RMAN Performance.