单项选择题 As shown in the diagram, in-memory statistics are transferred to the disk at regular intervals. Which background process performs this activity?（）

多项选择题 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?（）

多项选择题 You are using Recovery Manager (RMAN) to perform backups. In which three situations would you perform a compressed backup?（）