–T h e MAXOPENFILES  parameter defines how many files RMAN can read from the Oracle  source simultaneously. Set  MAXOPENFILES=1  so that RMAN does not read from more  than one file at a time. Example 20-6 shows a multiplexing calculation with various  FILESPERSET  and  MAXOPENFILES  settings. Figure 20-7 depicts a case study that shows the factoring ratio and a backup throughput  result with different multiplexing and parallel channel settings. The result is taken from a case  study of Oracle database backup with Tivoli Storage Manager, and a 30-day retention period  on ProtecTIER virtual tape. A full backup that is performed on alternate days averages a 5%  data change rate between the full backups.  Scenario 1: FILESPERSET=6, MAXOPENFILES=3, number of data files=4 Multiplex = 3 (Limiting by the MAXOPENFILES setting) Scenario 2: FILESPERSET=2, MAXOPENFILES=3, number of data files=4 Multiplex = 2 (Limiting by the FILESPERSET setting) Scenario 3: FILESPERSET=8, MAXOPENFILES=4, number of data files=2 Multiplex = 2 (Limiting by the number of data files) Scenario 4: FILESPERSET=1, MAXOPENFILES=1, number of data files=4 Multiplex = 1 (Limiting by the FILESPERSET and MAXOPENFILES settings) Example 20-6 Calculation of multiplexing in RMAN GLYPH<SM590000> Increase the number of parallel backup streams to improve backup throughput. Ensure  that the number of ProtecTIER virtual tape drives that are available for Oracle backup  matches the number of parallel streams that are configured in RMAN. For example, this  value is enabled in the definition of the Tivoli Storage Manager client on the Tivoli Storage  Manager server by using the  MAXNUMMP=32  parameter. Set  PARALLELISM=32  (up to 64). Figure 20-7 Example of multiplexing and parallelism effect on the HyperFactor ratio 316  IBM ProtecTIER Implementation and Best Practices Guide