Which statement is true about the execution of the command?

Correct answer is D

COMPRESSED Enables binary compression.
RMAN compresses the data written into the backup set to reduce the overall size of the backup set. All backups that create backup sets can create compressed backup sets. Restoring compressed backup sets is no different from restoring uncompressed backup sets.

RMAN applies a binary compression algorithm as it writes data to backup sets. This compression is similar to the compression provided by many media manager vendors. When backing up to a locally attached tape device, compression provided by the media management vendor is usually preferable to the binary compression provided by BACKUP AS COMPRESSED BACKUPSET. Therefore, use uncompressed backup sets and turn on the compression provided by the media management vendor when backing up to locally attached tape devices. You should not use RMAN binary compression and media manager compression together.

Some CPU overhead is associated with compressing backup sets. If the target database is running at or near its maximum load, then you may find the overhead unacceptable. In most other circumstances, compressing backup sets saves enough disk space to be worth the CPU overhead.

SECTION SIZE sizeSpec Specifies the size of each backup section produced during a data file backup.
By setting this parameter, RMAN can create a multisection backup. In a multisection backup, RMAN creates a backup piece that contains one file section, which is a contiguous range of blocks in a file. All sections of a multisection backup are the same size. You can create a multisection backup for a data file, but not a data file copy.

File sections enable RMAN to create multiple steps for the backup of a single large data file. RMAN channels can process each step independently and in parallel, with each channel producing one section of a multisection backup set.

If you specify a section size that is larger than the size of the file, then RMAN does not use multisection backup for the file. If you specify a small section size that would produce more than 256 sections, then RMAN increases the section size to a value that results in exactly 256 sections.

Depending on where you specify this parameter in the RMAN syntax, you can specify different section sizes for different files in the same backup job.

Note: You cannot use SECTION SIZE with MAXPIECESIZE or with INCREMENTAL LEVEL 1.