E20-526 · Question #60
A customer has recently deployed an XtremIO 20 TB two X-Brick cluster to run an existing instance of Oracle RAC previously leveraging VNX for back-end storage. The application environment uses a…
The correct answer is C. 64 or 128. Oracle Database performs I/O on data files in multiples of the database block size (db_block_size), which is 8KB by default. The default Oracle Database block size is optimal on XtremIO. XtremIO supports larger block sizes as well. In the case of multiblock I/O (e.g…
Question
A customer has recently deployed an XtremIO 20 TB two X-Brick cluster to run an existing instance of Oracle RAC previously leveraging VNX for back-end storage. The application environment uses a block size of 1 MB. Multiple tables are in use with the PARALLEL_DEGREE_POLICY variable set to AUTO. The customer wants your help with tuning the DB_FILE_MULTIBLOCK_READ_COUNT parameter for best performance with XtremIO. Which values should be recommended for tuning the DB_FILE_MULTIBLOCK_READ_COUNT parameter in the Oracle RAC environment?
Options
- A8 or 16
- B24 or 32
- C64 or 128
- D256 or 512
How the community answered
(42 responses)- A5% (2)
- B14% (6)
- C74% (31)
- D7% (3)
Explanation
Oracle Database performs I/O on data files in multiples of the database block size (db_block_size), which is 8KB by default. The default Oracle Database block size is optimal on XtremIO. XtremIO supports larger block sizes as well. In the case of multiblock I/O (e.g., table/index scans with access method full), one should tune the Oracle Database initialization parameter db_file_multiblock_read_count to limit the requests to 128KB. Therefore, the formula for db_file_multiblock_read_count is: db_file_multiblock_read_count = 128KB / db_block_size In our case the block size is 1 MB, so the formula db_file_multiblock_read_count is 1 MB/ 8KB =
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