You are managing an Oracle Database 11g database. You want to take the backup of
MULT_DATA, a big file tablespace of size 100 TB on tape drive, but you have tapedrives of
only 10 GB each.
Which method would accomplish the task quickly and efficiently?
A.
parallel image copy backup
B.
backup with MAXPIECESIZE configured for the channel
C.
parallel backup with MAXPIECESIZE configured for the channel
D.
intrafile parallel backup
Explanation:
The MAXPIECESIZE option is to limit the size of backup piece. not to split the big file into
pieces.
Configuring the Maximum Size of Backup Pieces
Backup piece size is an issue when it exceeds the maximum file size permitted by the file
system or media management software. You can use the MAXPIECESIZE parameter of the
CONFIGURE CHANNEL or ALLOCATE CHANNEL command to limit the size of backup
pieces.
For example, to limit the backup piece size to 2 gigabytes or less, you can configure the
automatic DISK channel as follows and then run BACKUP DATABASE:
CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 2G;BACKUP DATABASE;
We should use the SECTION SIZE option to split the big file into sections to the multiple
backup devices. 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.
The answer should be C, not D. “Quickly and efficiently” means parallel backup with MAXPIECESIZE.
I agree, C is the correct answer.
Here is why …
Below is an example using MAXPIECESIZE, see a few questions earlier for a similar example using SECTION SIZE.
I will use parallelism = 1
RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 2M;
new RMAN configuration parameters:
CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 2 M;
new RMAN configuration parameters are successfully stored
RMAN> BACKUP TABLESPACE users;
Starting backup at 05-MAR-16
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=161 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00004 name=D:\ORADATA\AHEADPRD\USERS01.DBF
channel ORA_DISK_1: starting piece 1 at 05-MAR-16
channel ORA_DISK_1: finished piece 1 at 05-MAR-16
piece handle=D:\FLASH_RECOVERY_AREA\AHEADPRD\BACKUPSET\2016_03_05\O1_MF_NNNDF_TAG20160305T184130_CFP6LC8G_.BKP tag=TAG20160305T184130 comment=NONE
channel ORA_DISK_1: starting piece 2 at 05-MAR-16
channel ORA_DISK_1: finished piece 2 at 05-MAR-16
piece handle=D:\FLASH_RECOVERY_AREA\AHEADPRD\BACKUPSET\2016_03_05\O1_MF_NNNDF_TAG20160305T184130_CFP6LD91_.BKP tag=TAG20160305T184130 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:02
Finished backup at 05-MAR-16
RMAN> LIST BACKUP;
…
BS Key Type LV Size Device Type Elapsed Time Completion Time
——- —- — ———- ———– ———— —————
20 Full 3.36M DISK 00:00:02 05-MAR-16
List of Datafiles in backup set 20
File LV Type Ckp SCN Ckp Time Name
—- — —- ———- ——— —-
4 Full 1994518 05-MAR-16 D:\ORADATA\AHEADPRD\USERS01.DBF
Backup Set Copy #1 of backup set 20
Device Type Elapsed Time Completion Time Compressed Tag
———– ———— ————— ———- —
DISK 00:00:02 05-MAR-16 NO TAG20160305T184130
List of Backup Pieces for backup set 20 Copy #1
BP Key Pc# Status Piece Name
——- — ———– ———-
22 1 AVAILABLE D:\FLASH_RECOVERY_AREA\AHEADPRD\BACKUPSET\2016_03_05\O1_MF_NNNDF_TAG20160305T184130_CFP6LC8G_.BKP
23 2 AVAILABLE D:\FLASH_RECOVERY_AREA\AHEADPRD\BACKUPSET\2016_03_05\O1_MF_NNNDF_TAG20160305T184130_CFP6LD91_.BKP
The Answer is D.
I suggest reading “Dividing the Backup of a Large Datafile into Sections”
http://docs.oracle.com/cd/E25054_01/backup.1111/e10642/rcmbckad.htm
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
I changed my mind on the answer to this question.
As Vamsi correctly pointed out above in
http://oracle.su/docs/11g/backup.112/e10642/rcmbckad.htm#sthref974 shows
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.
So that each of the SBT channels backs up a 10 GB file section
RMAN> RUN
{
ALLOCATE CHANNEL t1 TYPE SBT;
ALLOCATE CHANNEL t2 TYPE SBT;
ALLOCATE CHANNEL t3 TYPE SBT;
ALLOCATE CHANNEL t4 TYPE SBT;
BACKUP SECTION SIZE 10G TABLESPACE MULT_DATA;
}
you would need to configure
Note this does not use MAXPIECESIZE.
Hence C is wrong. The only possible other correct answer is D.
Please note that the version of oracle exam-ed in IZO-053 is 11.2.0.1 as stated here …
https://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=5001&get_params=p_exam_id:1Z0-053&p_org_id=&lang=
Therefore please refer to the 11.2.0.1 documentation found in …
http://oracle.su/docs/11g/nav/portal_booklist.htm
Just want to point out D will not work with the numbers in this question.
We can only have 256 sections at most and if each section can handle 10G, the total number it can handle is 2560G, which is smaller than the 100T for the big file.
There is no limitation for backup pieces number if we chooose the maxpiecesize option.