content_image/996832.jpg
–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. 

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) 

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 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. 

<img src='content_image/996832.jpg'>

