E x e r c i s e 4 .1   ( c o nt i n u e d )

CONFIGURE CONTROLFILE AUTOBACKUP ON;

new RMAN configuration parameters are successfully stored

5.Configure for compressed backup sets:

RMAN> CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO COMPRESSED BACKUPSET;

new RMAN configuration parameters:

CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO COMPRESSED BACKUPSET;

new RMAN configuration parameters are successfully stored

6.Create a directory to hold the snapshot control file (you will want to use your own directory paths, of course):

RMAN> host “mkdir \oracle01”; host command complete

RMAN> host “mkdir \oracle01\snapshot”; host command complete

7.Configure RMAN so the snapshot control file will be created in the new directory:

RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO ‘c:\oracle01\snapshot’; new RMAN configuration parameters:

CONFIGURE SNAPSHOT CONTROLFILE NAME TO ‘c:\oracle01\snapshot’; new RMAN configuration parameters are successfully stored

8.Exit RMAN:

RMAN> exit

Recovery Manager complete.

Backing Up Your Database with RMAN

We will discuss backups of your database using RMAN in the following sections. We will first talk about the different types of backups that you can make with RMAN. Then we will discuss what you can back up using RMAN, such as the database, archived redo logs, and so forth.

180  Chapter 4  n  Configuring and Backing Up Using RMAN

Using the RMAN Command Line

Like SQL and SQL*Plus, RMAN has its own unique command set. You use these commands to do a number of things:

This is just a partial list of all the things RMAN can do for you. Table 4.3 describes the RMAN commands you will need to be aware of for the OCP exam.

Ta b l e 4 . 3   ​  RMAN​ Commands

archivelogRecordSpecifier Specify a range of archived redo-log files.

image copies, which we will discuss later in this section). A given backup may create more than one backup set piece. A collection of related backup set pieces is called a backup set. A backup set is a logical entity that is used to maintain the association of independent backup set pieces.

In addition to multiple backup set pieces, you may have more than one backup set. This occurs when you parallelize a backup. Each channel will represent one backup set, each with its own backup set pieces. New backup sets will also be created on a channel if a backup set exceeds the backup set size limitations.

Note that a given datafile can span backup set pieces but cannot span backup sets. The ability of a given datafile to span backup set pieces is known as multiplexing. Multiplexing is another form of parallelization, as it allows RMAN to read from multiple datafiles in parallel and write them to a single backup set piece. Thus a given backup set piece may have data from many datafiles in it.

In the default RMAN configuration, a given tablespace/datafile backup may find itself in more than one backup set piece. However, each individual tablespace/datafile backup can be associated with only a single RMAN backup set and thus will be backed up by only one channel.

Oracle Database 11g has a new feature called multisection backups. Multisection backups allow you to parallelize the backup of large datafiles (bigfile tablespaces or normal tablespaces). You may well find questions on multisection backups on your OCP exam.

Figure 4.2 demonstrates the relationship between backups, backup sets, and backup set pieces.

F i g u r e 4 . 2   ​  Relationship​ between RMAN backups, backup sets, and backup set pieces

Backup

186  Chapter 4  n  Configuring and Backing Up Using RMAN

RMAN Image Copies

RMAN image copies are one-to-one copies of database datafiles. When you do an imagecopy backup of your database, you will receive no benefits of compression, so the disk-space requirement is a one-to-one requirement. Image copies must be made to disk. Figure 4.3 shows the difference between image and regular backups.

F i g u r e 4 . 3   ​  Image​ vs. regular backups

The upside to an image copy is that it can be much faster to restore. RMAN will always choose to restore image copies over backup sets if an image copy is available. In fact, using the switch to copy command makes it even faster, as RMAN will simply switch to the image copy on disk and start using that copy (applying redo as required). To make an image copy, use the backup as copy command, as shown in this example:

RMAN> Backup as copy database;

You can also make image copies of datafiles or tablespaces, as shown in these examples:

RMAN>backup as copy datafile 4;

RMAN>Backup as copy tablespace users;

If you prefer to always use image copies rather than backup sets, you can configure RMAN to do so by default with the configure command, as seen here:

configure device type disk backup type to copy;

RMAN can use a mixture of image copies, incremental backups, and archived redo logs when performing recovery (which we will discuss in more detail in Chapter 5). This can make total recovery of your database, a tablespace, or a datafile much quicker.

RMAN Offline Backups

We discussed manual offline backups in Chapter 2. Offline backups in RMAN are not much different except that you use the RMAN interface to actually do the backup rather than an OS file-copy utility. You will still need to close the database, but your backup will be done with the database in mount mode rather than completely shut down.

No parameter-file adjustments are required for an RMAN offline backup. We recommend that you configure and use the FRA (discussed earlier in this chapter) even if you are doing

offline backups. This makes for a standardized backup location and also allows the Oracle database to manage the overall backup space utilization more efficiently.

To perform an offline backup of your database with RMAN, follow these steps:

1.Start the RMAN client.

2.Shut down the database from the RMAN client, SQL*Plus, or OEM. The shutdown should be a consistent shutdown, so use the shutdown, shutdown immediate, or shutdown transactional command.

3.Start up the database in mount mode using the startup mount command.

4.Back up the database with the RMAN backup command:

RMAN>backup database;

5.When the backup is complete, open the database with the alter database open command.

RMAN Online Backups

For online backups in RMAN, the database must be configured in ARCHIVELOG mode (see Chapter 2 for more on configuring the database for ARCHIVELOG-mode operations). Once the database is configured properly, and RMAN is configured properly (as discussed earlier in this chapter), you can do online backups.

Online backups with RMAN are easy. You need to make sure the database and the archived redo logs are backed up; thus you issue the command backup database plus archivelog. That’s it. That command will create a recoverable backup of the database. This is known as a whole database backup.

If you want to delete the archived redo logs after the backup, you would append the delete input clause to the command. Other options are available depending on your needs.

In the following example we perform an online backup of our database using the backup as compressed backupset database plus archivelog delete input command. This will create a compressed backup of the database, backing up the archived redo logs and then deleting those backed-up archived redo logs after the backup is complete. Also note that we have configured control-file autobackups.

RMAN> backup as compressed backupset database plus archivelog delete input; Starting backup at 05-SEP-08

current log archived allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=131 device type=DISK

channel ORA_DISK_1: starting compressed archived log backup set channel ORA_DISK_1: specifying archived log(s) in backup set input archived log thread=1 sequence=41 RECID=40 STAMP=664583178 input archived log thread=1 sequence=42 RECID=41 STAMP=664621168

188  Chapter 4  n  Configuring and Backing Up Using RMAN

input archived log thread=1 sequence=43 RECID=42 STAMP=664650496 input archived log thread=1 sequence=44 RECID=43 STAMP=664655636 channel ORA_DISK_1: starting piece 1 at 05-SEP-08

channel ORA_DISK_1: finished piece 1 at 05-SEP-08

piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL\BACKUPSET\2008_09_05\ O1_MF_ANNNN_TAG20080905T183357_4D3N085C_.BKP tag=TAG20080905T183357 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:15 channel ORA_DISK_1: deleting archived log(s)

archived log file name=C:\ORACLE\ARCH\ORCL\ARC00041_0662757171.001 RECID=40 STAMP=664583178

archived log file name=C:\ORACLE\ARCH\ORCL\ARC00042_0662757171.001 RECID=41 STAMP=664621168

archived log file name=C:\ORACLE\ARCH\ORCL\ARC00043_0662757171.001 RECID=42 STAMP=664650496

archived log file name=C:\ORACLE\ARCH\ORCL\ARC00044_0662757171.001 RECID=43 STAMP=664655636

Finished backup at 05-SEP-08 Starting backup at 05-SEP-08 using channel ORA_DISK_1

channel ORA_DISK_1: starting compressed full datafile backup set channel ORA_DISK_1: specifying datafile(s) in backup set

input datafile file number=00002 name=C:\ORACLE\ORADATA\ORCL\SYSAUX01.DBF input datafile file number=00001 name=C:\ORACLE\ORADATA\ORCL\SYSTEM01.DBF input datafile file number=00005 name=C:\ORACLE\ORADATA\ORCL\UNDOTBS02.DBF input datafile file number=00004 name=C:\ORACLE\ORADATA\ORCL\USERS01.DBF channel ORA_DISK_1: starting piece 1 at 05-SEP-08

channel ORA_DISK_1: finished piece 1 at 05-SEP-08

piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL\BACKUPSET\2008_09_05\ O1_MF_NNNDF_TAG20080905T183432_4D3N0Z0Z_.BKP tag=TAG20080905T183432 comment=NONE

channel ORA_DISK_1: starting piece 2 at 05-SEP-08 channel ORA_DISK_1: finished piece 2 at 05-SEP-08

piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL\BACKUPSET\2008_09_05 \O1_MF_NNNDF_TAG20080905T183432_4D3N63Y8_.BKP tag=TAG20080905T183432 comment=NONE

channel ORA_DISK_1: starting piece 3 at 05-SEP-08 channel ORA_DISK_1: finished piece 3 at 05-SEP-08

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E x e r c i s e 4 . 2

Executing an Online Backup

In this exercise you will perform an online backup of your ARCHIVELOG mode database. Your database should already be in ARCHIVELOG mode (see Exercise 2.1). Once the database is in ARCHIVELOG mode you can do this exercise.

1.Log into the database using SQL*Plus:

C:\oracle\admin\ORCL\wallet>set oracle_sid=orcl C:\oracle\admin\ORCL\wallet>sqlplus “/ as sysdba”

SQL*Plus: Release 11.1.0.6.0 - Production on Thu Sep 11 18:56:27 2008 Copyright (c) 1982, 2007, Oracle. All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production With the Partitioning, OLAP, Data Mining and Real Application

Testing options SQL>

2.Query the LOG_MODE column of the V$DATABASE view to confirm that the database is in ARCHIVELOG mode. If the database is not in ARCHIVELOG mode, refer to Chapter 2 for information on how to put the database in ARCHIVELOG mode.

SQL> Select log_mode from v$database; LOG_MODE

------------

ARCHIVELOG

3.Exit SQL*Plus and start RMAN:

SQL> exit

Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

C:\oracle\admin\ORCL\wallet>rman target=/

Recovery Manager: Release 11.1.0.6.0 - Production on Thu Sep 11 18:58:55 2008

Copyright (c) 1982, 2007, Oracle. All rights reserved. connected to target database: ORCL (DBID=1190537904)

4.Execute the RMAN backup using the backup database command. Back up the archived redo logs at the same time with the plus archivelog option. Remove the archived redo logs after they are backed up using the delete input option.

RMAN> Backup database plus archivelog delete input;

E x e r c i s e 4 . 2   ( c o nt i n u e d )

5.Review the output, and make sure the backup was successful. Here is an example of our output. We bolded the messages that indicate a successful backup.

RMAN> Backup database plus archivelog delete input; Starting backup at 11-SEP-08

current log archived

using target database control file instead of recovery catalog allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=128 device type=DISK

channel ORA_DISK_1: starting compressed archived log backup set channel ORA_DISK_1: specifying archived log(s) in backup set input archived log thread=1 sequence=87 RECID=86 STAMP=665092065 input archived log thread=1 sequence=88 RECID=87 STAMP=665138962 input archived log thread=1 sequence=89 RECID=88 STAMP=665172239 input archived log thread=1 sequence=90 RECID=89 STAMP=665172313 input archived log thread=1 sequence=91 RECID=90 STAMP=665172466 input archived log thread=1 sequence=92 RECID=91 STAMP=665175694 channel ORA_DISK_1: starting piece 1 at 11-SEP-08

channel ORA_DISK_1: finished piece 1 at 11-SEP-08 piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL

\BACKUPSET\2008_09_11\O1_MF_ANNNN_TAG20080911T190135_4DMHVZFK_.BKP tag=TAG20080911T190135 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:07 channel ORA_DISK_1: deleting archived log(s)

archived log file name=C:\ORACLE\ARCH\ORCL\ ARC00087_0662757171.001 RECID=86 STAMP=665092065 archived log file name=C:\ORACLE\ARCH\ORCL\ ARC00088_0662757171.001 RECID=87 STAMP=665138962 archived log file name=C:\ORACLE\ARCH\ORCL\ ARC00089_0662757171.001 RECID=88 STAMP=665172239 archived log file name=C:\ORACLE\ARCH\ORCL\ ARC00090_0662757171.001 RECID=89 STAMP=665172313 archived log file name=C:\ORACLE\ARCH\ORCL\ ARC00091_0662757171.001 RECID=90 STAMP=665172466 archived log file name=C:\ORACLE\ARCH\ORCL\ ARC00092_0662757171.001 RECID=91 STAMP=665175694

Finished backup at 11-SEP-08

Starting backup at 11-SEP-08 using channel ORA_DISK_1

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E x e r c i s e 4 . 2   ( c o nt i n u e d )

channel ORA_DISK_1: starting compressed full datafile backup set channel ORA_DISK_1: specifying datafile(s) in backup set

input datafile file number=00002 name=C:\ORACLE\ORADATA\ORCL\SYSAUX01.DBF input datafile file number=00001 name=C:\ORACLE\ORADATA\ORCL\SYSTEM01.DBF input datafile file number=00005 name=C:\ORACLE\ORADATA\ORCL\UNDOTBS02.DBF input datafile file number=00004 name=C:\ORACLE\ORADATA\ORCL\USERS01.DBF

channel ORA_DISK_1: starting piece 1 at 11-SEP-08 channel ORA_DISK_1: finished piece 1 at 11-SEP-08 piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL

\BACKUPSET\2008_09_11\O1_MF_NNNDF_TAG20080911T190200_4DMHWM1T_.BKP tag=TAG20080911T190200 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:05:36

Finished backup at 11-SEP-08 Starting backup at 11-SEP-08 current log archived

using channel ORA_DISK_1

channel ORA_DISK_1: starting compressed archived log backup set channel ORA_DISK_1: specifying archived log(s) in backup set input archived log thread=1 sequence=93 RECID=92 STAMP=665176062 channel ORA_DISK_1: starting piece 1 at 11-SEP-08

channel ORA_DISK_1: finished piece 1 at 11-SEP-08 piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL

\BACKUPSET\2008_09_11\O1_MF_ANNNN_TAG20080911T190742_4DMJ7H29_.BKP tag=TAG20080911T190742 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01 channel ORA_DISK_1: deleting archived log(s)

archived log file name=C:\ORACLE\ARCH\ORCL \ARC00093_0662757171.001 RECID=92 STAMP=665176062

Finished backup at 11-SEP-08

Starting Control File and SPFILE Autobackup at 11-SEP-08 piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL

\AUTOBACKUP\2008_09_11\O1_MF_S_665176080_4DMJ7SOT_.BKP comment=NONE

Finished Control File and SPFILE Autobackup at 11-SEP-08

194  Chapter 4  n  Configuring and Backing Up Using RMAN

To create the block-tracking file, use the alter database enable block change tracking command. By default, Oracle will create the block-change tracking file in the location defined by the DB_CREATE_FILE_DEST parameter. If that parameter is not set, Oracle will require that you provide a destination and filename for the block-change tracking file. Here is an example of the creation of a block-change tracking file:

SQL> alter database enable block change tracking using file ‘c:\oracle\block_change_tracking\orcl_block_change.fil’;

You can find the location of the current block-change tracking file by looking at the

FILENAME column of the V$BLOCK_CHANGE_TRACKING view. You can use the STATUS column of the V$BLOCK_CHANGE_TRACKING view to determine if block-change tracking is enabled.

You should perform a level 0 incremental backup after creating the blockchange tracking file. This is because the parent level-0 backup bitmap must be in the block-change tracking file.

Types of Incremental Backups

Two types of incremental backups are available for you to choose from:

The level-0 backup is like a full backup (sometimes it’s called a base backup), except that incremental backups can be based on it (they can not be based on a regular full backup).

The level-1 backup is the incremental backup that backs up changed blocks. There are two different kinds of level-1 backups:

The differential incremental backup will back up all changed blocks since the last level-1 backup. These images are typically smaller. The cumulative incremental backup is one where the data backed up is the data that changed since the last level-0 full backup. Thus it is a cumulative backup of all changed blocks since the last level-0 backup. This makes for faster recoveries since you don’t have to apply several incremental backups during the database restore. Figure 4.5 provides a visual example of the differences between these types of backups.

Performing Incremental Backups

Performing incremental backups is almost exactly like performing regular backups except that you include the incremental level option in the backup command. For example, to create a base, level-0 backup, you would issue this command:

RMAN> Backup as compressed backupset incremental level 0 database plus archivelog delete input;

When you are ready to run your first incremental backup you would use the backup command with the incremental level-1 option, as shown here:

RMAN> Backup as compressed backupset incremental level 1 database plus archivelog delete input;

Differential backups are the default type of incremental backup in Oracle. If you want to perform a cumulative backup, you will need to include the cumulative keyword, as shown here:

RMAN> Backup as compressed backupset incremental level 1 cumulative database plus archivelog delete input;

196  Chapter 4  n  Configuring and Backing Up Using RMAN

Note that if you try to do a level-1 backup and a level-0 does not exist, RMAN will not generate an error. It will simply perform a level-0 backup for you instead.

RMAN Incrementally Updated Backups

Incrementally updated backups involve a combination of a full image backup of the database and then subsequent level-1 incremental backups of the database, which are applied to the image-copy backup. An incrementally updated backup makes for a quicker restore but for a bigger backup image.

To create an incrementally updated backup, all you need do is run the following script:

RUN { # the recover copy command does not really recover anything.

#it simply tells RMAN that the incremental to be executed should

#be applied to the database copy we made above.

Recover copy of database with tag ’Jacob_Jared_Lizzie’; Backup incremental level 1

for recover of copy with tag ’Jacob_Jared_Lizzie’ Database; }

On the first execution of this script, RMAN will detect that no backup copy exists. Warnings will be generated, but no errors. RMAN will proceed to create the initial copy of the database. No incremental copy will be created.

On subsequent executions, RMAN will detect that an image copy does exist, and it will then apply the previous level-1 incremental-and then execute another level-1 incremental backup. Note that on the second run, RMAN will detect that no incremental backup exists to apply to the datafile copy and a warning will be raised because of this. That is normal.

This method limits the recovery window for your database to one day. For example, if you executed this script on day 1, day 2, and day 3, after day 3’s execution you would not be able to restore your database to any point before day 3’s backup.

You could provide for longer recovery windows by including the until time clause. In this example, we allow for a recovery window of five days:

RMAN Multisection Backups

Prior to Oracle Database 11g, you could not parallelize the backup of a given database datafile. Since datafiles had to be contained wholly within a single backup set, this meant that the backup of that datafile was serialized. This can be a bit of a problem if your database consists of one or two huge datafiles and several smaller datafiles. Also, if you are using bigfile tablespaces, the lack of inner-file backup parallelization could be a big issue.

Oracle Database 11g provides a new feature called multisection backups that provides the ability to parallelize the backup of a single datafile. This feature is supported by the section size clause in the backup command followed by the desired section size. Here is an example:

RMAN> backup section size 40m database;

In this example, RMAN will chunk up each datafile into 40MB chunks, and each allocated channel can process those individual 40MB chunks. Note that if you allocate only one channel, only one chunk at a time will get backed up! Also note that the size parameter does not indicate the size of the resulting backup set piece. Rather, it is the equivalent amount of data within the datafile that each RMAN channel will process. The resulting pieces can vary wildly in size.

RMAN Backup of Archived Redo Logs

Backing up archived redo logs is an important task since it serves to protect the database’s principal recovery mechanism, which is redo. Backing up archived redo logs is done via the backup archivelog command. This command requires that you include keywords from the archivelog specifier clause, which is used to indicate the archived redo logs that you want to back up. Common keywords that you might use include the following:

NN All: Backs up all archived redo logs currently on disk

NNSequence between n and o: Backs up all archived redo logs available on disk between sequence number n and sequence number o

NNTime between t1 and t2: Backs up all archived redo logs available on disk between time t1 (the earlier time) and time t2 (the later time)

Here is an example of backing up all archived redo logs, still on disk, that were generated in the last 24 hours:

RMAN> backup archivelog time between “sysdate-1” and “sysdate”; Starting backup at 05-SEP-08

using channel ORA_DISK_1

channel ORA_DISK_1: starting archived log backup set channel ORA_DISK_1: specifying archived log(s) in backup set

input archived log thread=1 sequence=46 RECID=45 STAMP=664657241 channel ORA_DISK_1: starting piece 1 at 05-SEP-08

channel ORA_DISK_1: finished piece 1 at 05-SEP-08

piece handle=C:\ORACLE\FLASH_RECOVERY_AREA\ORCL\BACKUPSET\2008_09_05\ O1_MF_ANNNN_TAG20080905T190103_4D3OLO2G_.BKP tag=TAG20080905T190103 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01 Finished backup at 05-SEP-08.

198  Chapter 4  n  Configuring and Backing Up Using RMAN

Be Careful What You Ask For...You Might Just Get It (Or Not)

Look at the example where we backed up the archived redo logs for the last 24 hours. The command was as follows:

backup archivelog time between “sysdate-1” and “sysdate”;

But guess what happens if you change this command just slightly:

RMAN> backup archivelog time between “sysdate” and “sysdate-1”; Starting backup at 05-SEP-08

using channel ORA_DISK_1

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of backup command at 09/05/2008 19:02:56 RMAN-20242: specification does not match any archived log in the recovery catalog

If you didn’t know any better, you might just think that there are no archived redo logs to back up and assume the backup archivelog command worked fine and dandy. In fact, the command failed because you had the from/to dates in the wrong order. This highlights how important it is to make sure you carefully review the syntax of the command you are getting ready to execute and then review the output of RMAN commands and make sure RMAN did what you thought you told it to do.

RMAN Backup of the Spfile and Control Files

We have already discussed control-file autobackups in this chapter. You may find that on occasion you want to do an individual backup of the control file or the spfile.

You have two options in RMAN for control-file backups, using the backup current controlfile command or the backup controlfilecopy command.

The backup as copy command will cause the current control file to be backed up. This is a copy of the control file, so it’s like a backup control file. Thus, you could just copy the file into place and treat it as a backup control file. By default the backup will be created in the FRA as would happen in this example:

RMAN> backup as copy current controlfile;