Exam 1z0-083 topic 1 question 2 discussion

DE correct C = incorrect, rman does not use database buffer cache

A) is used for copy/write tuning tape is sync, but read is on disks, so async IO can be used for reading blocks

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

DE 100% sure

DE - see Raferen10

how do we enable async io?

D and E are correct

RMAN is not using db buffere so C is incorrect

It's DE.

DE correct https://docs.oracle.com/en/database/oracle/oracle-database/19/bradv/tuning-rman-performance.html#GUID-3303B929-0747-4E78-BED1-9F468213F357

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.

AE. D async is for writes, not reads.

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.

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.

CE correct