Oracle Database Administration II — Question 74

While backing up to the Oracle Fast Recovery Area (FRA), you determined the backup is taking too long and suspect a performance bottleneck.
Which three are true about diagnosing and tuning these problems? (Choose three.)

Answer options

• A. If an RMAN BACKUP VALIDATE command takes roughly the same time as an actual backup, then both read and write I/O are likely bottlenecks.
• B. Setting DBWR_IO_SLAVES to a non zero value can improve backup performance when using synchronous I/O.
• C. If an RMAN BACKUP VALIDATE command takes noticeably less than an actual backup, then write I/O is a likely bottleneck.
• D. If an RMAN BACKUP VALIDATE command takes roughly the same time as an actual backup, then read I/O is a likely bottleneck.
• E. Data files with a high value in V$BACKUP_SYNC_IO.DISCRETE_BYTES_PER_SECOND are a potential performance bottleneck when synchronous I/O is used.
• F. Setting DBWR_IO_SLAVES to a non zero value can improve backup performance when using asynchronous I/O/
• G. Data files with a high value in V$BACKUP_ASYNC_IO.SHORT_WAITS are a potential performance bottleneck when asynchronous I/O is used.

Correct answer: B, C, D

Explanation

Option B is correct because increasing DBWR_IO_SLAVES can help with the performance of backups when synchronous I/O is in play. Option C is also accurate as it indicates that a significantly shorter time for validation suggests write I/O issues. Option D is valid because if the validation time matches the backup time, it points to read I/O problems. Options A, E, F, and G are incorrect as they either misrepresent the relationship between I/O types and performance or focus on scenarios not relevant to the specific bottleneck diagnosis.