While backing up to an SBT channel, you determine that the read phase of your compressed Recovery Manager (RMAN) incremental level 0 backup is a bottleneck.
FORCE LOGGING is enabled for the database.
Which two could improve read performance? (Choose two.)
To improve the read performance during the RMAN incremental level 0 backup, enabling asynchronous disk I/O allows multiple I/O operations to be initiated before waiting for any to complete, enhancing efficiency. Additionally, increasing the level of RMAN multiplexing helps by allowing more simultaneous read operations, which can further speed up the backup process by filling tape buffers faster and ensuring that the system handles more data concurrently.
DE correct C = incorrect, rman does not use database buffer cache
AE, io on tape is sync
A) is used for copy/write tuning https://docs.oracle.com/html/E10642_06/rcmtunin.htm#i1006396 tape is sync, but read is on disks, so async IO can be used for reading blocks
I agree, D is correct > In RMAN operation, asynchronous Disk I/O is always better than synchronous I/O as a server process can begin an I/O and then perform other work while waiting for the I/O to complete. On operating systems that do not support native asynchronous I/O, the database can simulate it with special I/O slave processes (DBWR_IO_SLAVES)
Agree that rman doesn't use db buffer cache: RMAN Backup Performance (Doc ID 360443.1) "RMAN uses its own buffer cache separate from the database buffer cache"
When a channel reads from or writes to disk, the I/O is either synchronous I/O or asynchronous I/O. When the disk I/O is synchronous, a server process can perform only one task at a time. When the disk I/O is asynchronous, a server process can begin an I/O operation and then perform other work while waiting for the I/O to complete. RMAN can also begin multiple I/O operations before waiting for the first to complete. When reading from an ASM disk group, you should use asynchronous disk I/O if possible. Also, if a channel reads from a raw device managed with a volume manager, then asynchronous disk I/O also works well. Some operating systems support native asynchronous disk I/O. The database takes advantage of this feature if it is available.
RMAN is not using db buffere so C is incorrect
C is incorrect. RMAN does not use database buffer cache. The answer is D,E. Asynchronous I/O (D) and multiplexing (Parallel read - E) improve read performance.
You can improve performance by increasing the degree of multiplexing used for backing up. This increases the rate at which RMAN fills tape buffers, which makes it more likely that buffers are sent to the media manager fast enough to maintain streaming.
It's DE.
CE correct
Do you mean to say (based on your analysis), that DE is correct? D. Enable asynchronous disk I/O. E. Increase the level of RMAN multiplexing.
The correct answers are D and E. These solutions specifically address the bottleneck in the read phase of RMAN incremental level 0 backups to an SBT (System Backup to Tape) channel, especially when FORCE LOGGING is enabled for the database. https://tinyurl.com/48j924rw Just took my exams and scored flying colors with the help of this exams dumps
DE 100% sure
DE - see Raferen10
Correct: D,E A. False. SBT buffer can't help on READ phase B. False. Force logging causes all operations in the database to be written to files, but it has no relation to RMAN reading performance C. False. RMAN uses its own buffer cache separate from the database buffer cache D. True. In RMAN operation, asynchronous Disk I/O is always better than synchronous I/O as a server process can begin an I/O and then perform other work while waiting for the I/O to complete.On operating systems that do not support native asynchronous I/O, the database can simulate it with special I/O slave processes (DBWR_IO_SLAVES) E. True. Parallel read
how do we enable async io?
D and E are correct
DE correct https://docs.oracle.com/en/database/oracle/oracle-database/19/bradv/tuning-rman-performance.html#GUID-3303B929-0747-4E78-BED1-9F468213F357
AE. D async is for writes, not reads.
No, you are totally wrong… Synchronous and Asynchronous Disk I/O When a channel reads from or writes to disk, the I/O is either synchronous I/O or asynchronous I/O. When the disk I/O is synchronous, a server process can perform only one task at a time. When the disk I/O is asynchronous, a server process can begin an I/O operation and then perform other work while waiting for the I/O to complete. RMAN can also begin multiple I/O operations before waiting for the first to complete. Take a look at https://docs.oracle.com/database/121/BRADV/rcmtunin.htm#BRADV90067 and Focus on the Read-Phase
Yep, you're right. async can help at READ phase, and A. SBT buffer can't help on READ phase. So finally right answer are: DE