You are managing an Oracle Database 11g database. You want to take a backup on tape
drives of the USERS tablespace that has a single data file of 900 MB. You have tape drives
of 300 MB each. To accomplish the backup, you issued the following RMAN command:
RMAN>BACKUP
SECTION SIZE 300M
TABLESPACE users;
What configuration should be effected to accomplish faster and optimized backups by using
the above command?
A.
The SBT channel must be configured, with the default parallelism setting for the SBT
device set to 1.
B.
The COMPATIBLE initialization parameter for the database instance must be set to at
least 10.0.
C.
The SBT channel must be configured, with the parallelism setting for the SBT device set
to 3.
D.
The SBT channel must be configured, with the MAXPIECESIZE set to 300 MB.
Explanation:
Dividing the Backup of a Large Data File into Sections (link)
If you specify the SECTION SIZE parameter on the BACKUP command, then RMAN creates
a backup set in which each backup piece contains the blocks from one file section. A file
section is a contiguous range of blocks in a file. This type of backup is called a multisection
backup.
Note: You cannot specify SECTION SIZE with MAXPIECESIZE.
The purpose of multisection backups is to enable RMAN channels to back up a single large
file in parallel. RMAN divides the work among multiple channels, with each channel backing
up one file section in a file. Backing up a file in separate sections can improve the
performance of backups of large datafiles.
If a multisection backup completes successfully, then none of the backup sets generated
during the backup contain a partial data file. If a multisection backup is unsuccessful, then it
is possible for the RMAN metadata to contain a record for a partial backup set. RMAN does
not consider partial backups for restore and recovery. You must use the DELETE command
to delete the partial 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.
To make a multisection backup:
1. Start RMAN and connect to a target database and recovery catalog (if used).
2. If necessary, configure channel parallelism so that RMAN can make the backup parallel.
3. Execute BACKUP with the SECTION SIZE parameter.
For example, suppose that the users tablespace contains a single data file of 900 MB. Also
assume that three SBT channels are configured, with the parallelism setting for the SBT
device set to 3. You can break up the data file in this tablespace into file sections as shown
in the following example:
BACKUP
SECTION SIZE 300M
TABLESPACE users;
In this example, each of the three SBT channels backs up a 300 MB file section of the users
data file.