Immediately after adding a new disk to or removing an existing disk from an ASM instance, you find that the performance of the database goes down initially until the time the addition or removal process is completed, and then gradually becomes normal.
Which two activities would you perform to maintain a consistent performance of the database while adding or removing disks?（）

You upgraded from a previous Oracle database version to Oracle Database version to Oracle Database12c. Your database supports a mixed workload. During the day, lots of insert, update, and deleteoperations are performed. At night, Extract, Transform, Load (ETL) and batch reporting jobs are run.
The ETL jobs perform certain database operations using two or more concurrent sessions.After the upgrade, you notice that the performance of ETL jobs has degraded. To ascertain the cause ofperformance degradation, you want to collect basic statistics such as the level of parallelism, totaldatabase time, and the number of I/O requests for the ETL jobs.
How do you accomplish this?（）

You notice a performance change in your production Oracle 12c database. You want to know which change caused this performance difference.
Which method or feature should you use?（）

You are working on a 24X7 database. You want to design a backup strategy for your database that uses user managed backups. You want to be able to perform all backups while the database remains online.
Which statement about performing user-managed backups in a 24x7 environment is true?（）

You are using a recovery catalog to maintain Recovery Manager (RMAN) backup information for yourproduction database. You have registered your production database and are performing regular backups.
Because of a new requirement you have added a few new tablespaces to your production database and youwant them to be included in backups.Identify two options for completing this task. （）(Choose two.)