This article presents an overview of all Oracle9i RMAN configuration parameters and examples of how they can be set.

RMAN> SHOW ALL;

RMAN configuration parameters are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/9.2.0/dbs/snapcf_TARGDB.f'; # default

• The default retention policy. This determines which backups and copies are eligible for deletion because they are no longer needed.

• Turning ON and OFF backup optimization. Backup optimization eliminates duplicate backups of identical datafiles (like those associated with a read-only tablespace) and archived redo logs.

• A default device type for RMAN jobs, (disk or tape [sbt])

• The default for automated backups of the control file to ON or OFF. You can also control the default format of the control file backup output files and the default device on which to create these backups.

• The number of channels (for parallelization) that are automatically allocated when performing automated backup and recovery/restore jobs.

• A tablespace exclusion policy to configure specific tablespaces to be excluded during full database backup operations. If there are no tablespace exclusion policies defined, nothing will be displayed by the show all command.

• The maximum size for any given backup piece and the size of any backup set when performing automated backups.

• The default filename for the snapshot controlfile.

This article will provide detailed information on all of these RMAN configuration parameters and how they can be defined.

Format	Description
%p	specifies the backup piece number within the backup set. This value starts at 1 for each backup set and is incremented by 1 as each backup piece is created.
%s	specifies the backup set number. This number is a counter in the control file that is incremented for each backup set. The counter value starts at 1 and is unique for the lifetime of the control file. If you restore a backup control file, then duplicate values can result. Also, CREATE CONTROLFILE initializes the counter back to 1.
%d	specifies the database name.
%n	specifies the database name, padded on the right with 'x' characters to a total length of 8 characters. For example, if PROD1 is the database name, then PROD1xxx is the padded database name.
%t	specifies the backup set timestamp, which is a 4-byte value derived as the number of seconds elapsed since a fixed reference time. The combination of %s and %t can be used to form a unique name for the backup set.
%u	specifies an 8-character name constituted by compressed representations of the backup set number and the time the backup set was created.
%c	(Oracle8i or higher) - specifies the copy number of the backup piece within a set of duplexed backup pieces. If you did not issue the set duplex command, then this variable will be 1 for regular backup sets and 0 for proxy copies. If you issued set duplex, the variable identifies the copy number: 1, 2, 3, or 4.
%U	(Oracle8i or higher) - specifies a convenient shorthand for %u_%p_%c that guarantees uniqueness in generated backup filenames. If you do not specify a format, RMAN uses %U by default. %U is the default in Oracle8i.

To set the MAXSETSIZE parameter back to its default value of UNLIMITED:

RMAN> configure maxsetsize clear;

RMAN> CONFIGURE RETENTION POLICY CLEAR;
RMAN> CONFIGURE BACKUP OPTIMIZATION CLEAR;
RMAN> CONFIGURE DEFAULT DEVICE TYPE CLEAR;
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP CLEAR;
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK CLEAR;
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE SBT CLEAR;
RMAN> CONFIGURE DEVICE TYPE DISK CLEAR;
RMAN> CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK CLEAR;
RMAN> CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE SBT  CLEAR;
RMAN> CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK CLEAR;
RMAN> CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE SBT CLEAR;
RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK CLEAR;
RMAN> CONFIGURE CHANNEL DEVICE TYPE SBT CLEAR;
RMAN> CONFIGURE MAXSETSIZE CLEAR;
RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME CLEAR;
RMAN> # CONFIGURE EXCLUDE FOR TABLESPACE USERS_READ_TBS;

CONFIGURE RETENTION POLICY TO REDUNDANCY 2;

CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 3 DAYS;

If back up your database infrequently, you probably will prefer a redundancy policy that is stated in terms of number of backups rather than backups later than n days old. In this case, you would use the redundancy parameter as follows:

RMAN> CONFIGURE RETENTION POLICY TO REDUNDANCY 3;

RMAN> CONFIGURE RETENTION POLICY TO NONE;

For archive logs, the same file means the same dbid, thread, sequence, and resetlogs data. If the DELETE INPUT option is used, RMAN deletes all the files that would have been backed up, even when the file is not included due to file optimization.

The two possible values for backup optimization is ON and OFF as shown in the following example syntax:

CONFIGURE BACKUP OPTIMIZATION OFF;

CONFIGURE BACKUP OPTIMIZATION ON;

Also note that you should consider how backup optimization works with regards to the RETENTION POLICY. RMAN will only work with files within the retention period. For example, consider performing a backup with optimization enabled and a retention period of 3 days. RMAN will only compare the datafile with backup sets within the 3 day period - even if the datafile it is about to backup hasn't changed within that 3 days.

The following two examples show the syntax for configuring the default device type to TAPE (SBT) - then another command to re-configure the default device type to DISK:

CONFIGURE DEFAULT DEVICE TYPE TO DISK;

CONFIGURE DEFAULT DEVICE TYPE TO SBT;

CONFIGURE CONTROLFILE AUTOBACKUP ON;

CONFIGURE CONTROLFILE AUTOBACKUP OFF;

• After every BACKUP or COPY command issued at the RMAN prompt.
• Whenever a BACKUP or COPY command within a RUN block is followed by a command that is neither BACKUP nor COPY.
• At the end of every RUN block if the last command in the block was either BACKUP or COPY.
• After database structural changes such as adding a new tablespace, altering the state of a tablespace or datafile (for example, bringing it online), adding a new online redo log, renaming a file, adding a new redo thread, and so forth. This type of autobackup, unlike autobackups that occur in the preceding circumstances, goes only to disk. You can run: CONFIGURE CONTROLFILE AUTOBACKUP FOR DEVICE TYPE DISK to set a nondefault disk location.

The "first channel" allocated during the BACKUP or COPY job creates the autobackup and places it "into its own backup set"; for post-structural autobackups, the "default disk channel" makes the backup.

RMAN writes both the CONTROLFILE and the SPFILE (if the database was started with an SPFILE) to the same backup piece. After the CONTROLFILE AUTOBACKUP completes, Oracle writes a message containing the complete path of the backup piece and the device type to the alert log.

RMAN automatically backs up the current control file using the default format of %F (see entry for CONFIGURE CONTROLFILE AUTOBACKUP FORMAT for an explanation of this substitution variable). You can change this format using the CONFIGURE CONTROLFILE AUTOBACKUP FORMAT and SET CONTROLFILE AUTOBACKUP FORMAT commands.

When this feature is disabled, any BACKUP command that includes datafile 1 (including BACKUP DATABASE) automatically includes the current control file and server parameter file in the backup set. Otherwise, RMAN does not include these files.

NOTE: You may see occasions where RMAN will sometimes automatically include the CONTROLFILE and SPFILE in the backupsets during a backup. This is normal and is documented (above). When CONTROLFILE AUTOBACKUP is not enabled, the CONTROLFILE and SPFILE, (if the database was started with an spfile), are included automatically when datafile 1 is backed up. Consider the following backup: RMAN> backup datafile 1; It will include the CONTROLFILE and the SPFILE (when the database is started with a spfile).

• IIIIIIIIII - stands for the DBID. (The DBID is printed in decimal so that it can be easily associated with the target database.
• YYYYMMDD - is a time stamp in the Gregorian calendar of the day the backup is generated.
• QQ - is the sequence in hexadecimal number that starts with 00 and has a maximum of 'FF' (256).

Specify CLEAR to return the format to the default %F.

NOTE: The %F tag is essential for RMAN to be able to restore the file without a recovery catalog.

Here is an example of how to set the format of the autobackup controlfile:

CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/orabackup/rman/ORA920/%F';

The PARALLELISM parameter specifies the number of automatic channels of the specified device type allocated for RMAN jobs. RMAN always allocates the number of channels specified by PARALLELISM, although it may actually use only a subset of these channels. By default, PARALLELISM = 1.

Take the following example; you can set PARALLELISM for DISK backups to 3. If you configure automatic channels of type disk and tape, and set the default device type as disk, then RMAN allocates three disk channels when you run BACKUP DATABASE at the RMAN prompt.

To change the parallelism for a device type to [n], run:

CONFIGURE DEVICE TYPE [DISK | SBT] PARALLELISM [n];

Here are several examples of how to configure PARALLELISM to 3 for sbt and then change it to 2:

CONFIGURE DEVICE TYPE sbt PARALLELISM 3;
CONFIGURE DEVICE TYPE sbt PARALLELISM 2;

Another example that configures parallelism to 2 for automatic disk channel.

CONFIGURE DEVICE TYPE DISK PARALLELISM 2;

NOTE: If you configure [n] manually numbered channels, the PARALLELISM setting can be greater than or less than [n]. For example, you can manually number 10 automatic channels and configure PARALLELISM to 2 or even 12.

Here is the general syntax:

    {ARCHIVELOG| DATAFILE}
        BACKUP COPIES FOR DEVICE
        TYPE deviceSpecifier
        TO integer;

NOTE: Control file autobackups on disk are a special case and are never duplexed. RMAN always writes one and only copy.

Here are several examples of how to set this parameter:

CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2;
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 2;

To clear this parameter, use the following:

CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK CLEAR;
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK CLEAR;

Next let's look at setting defaults for channels. You can either set default settings for all channels with the configure channel device type command or you can set defaults for a specific channel using the configure channel n device type, where n is the channel you want to set for.

Now, let's take a look at the general syntax:

    CHANNEL integer DEVICE TYPE deviceSpecifier allocOperandList;

            integer              You can specify a channel by number. You may
                                 also exclude an integer, in which case you
                                 are specifying a general channel.
            deviceSpecifier      {DISK | SBT}
            allocOperandList     /* Specifies control options for the  */
                                 /* allocated channel                  */
                                 [PARMS         = 'channel_parms']
                                 [CONNECT       = (quoted string)]
                                 [FORMAT        = 'format_sring']
                                 [MAXPIECESIZE  = integer [K|M|G]]
                                 [RATE          = integer [K|M|G]]
                                 [MAXOPENFILES  = integer]
                                 [SEND          = 'command']

    %d      Database name
    %s      Backup set number
    %p      Backup piece number
    %t      4-byte timestamp

Default Device Type	Default Name Format	Example
Disk	ORA_DISK_n	ORA_DISK_1, ORA_DISK_2
Tape	ORA_SBT_TAPE_n	ORA_SBT_TAPE_1, ORA_SBT_TAPE_1

Now let's look at setting the number of channels to be allocated during an automated backup or recovery operation. This example will set the default level of parallelism for disk operations to two. Now, if an automated backup is started, two channels will be allocated to perform the backup in parallel:

RMAN> CONFIGURE DEVICE TYPE DISK PARALLELISM 2;
RMAN> CONFIGURE CHANNEL 1 DEVICE TYPE DISK FORMAT '/orabackup1/rman/ORA920/backup_db_%d_S_%s_P_%p_T_%t';
RMAN> CONFIGURE CHANNEL 2 DEVICE TYPE DISK FORMAT '/orabackup2/rman/ORA920/backup_db_%d_S_%s_P_%p_T_%t';

You can also control the size of a backup set piece or the entire backup itself. In the following example, I will limit channel 1 to create each individual backup piece at a maximum size of 1024MB. Take note that this command does not limit the overall size of the backup:

RMAN> CONFIGURE CHANNEL 1 DEVICE TYPE DISK FORMAT '/orabackup1/rman/ORA920/backup_db_%d_S_%s_P_%p_T_%t' MAXPIECESIZE 1024m;

You can also set to limit all channels to have a limit of 1024MB by using:

RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT '/orabackup/rman/ORA920/backup_db_%d_S_%s_P_%p_T_%t' MAXPIECESIZE 1024m;

You can also limit the speed or rate of the backup channel:

RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT '/orabackup/rman/ORA920/backup_db_%d_S_%s_P_%p_T_%t' MAXPIECESIZE 1024m RATE 5m;

NOTE: If you configure a generic channel (that is, if you do not specify a channel number), then RMAN uses the generic settings for every parallelized channel except any channel number that you have explicitly configured. In other words, a generic channel setting specifies options for all channels not configured explicitly.

NOTE: The RATE parameter is intended to slow down a backup so that you can run it in the background with as little effect as possible on OLTP operations. The RATE parameter specifies units of bytes/second. Test to find a value that improves performance of your queries while still letting RMAN complete the backup in a reasonable amount of time. Note that RATE is not designed to increase backup throughput, but to decrease backup throughput so that more disk bandwidth is available for other database operations.

NOTE: The CONNECT parameter specifies a connect string to the database instance where RMAN should conduct the backup or restore operations. Use this parameter to spread the work of backup or restore operations across different instances in an Oracle Real Application Clusters configuration. If you do not specify this parameter, and if you did not specify the AUXILIARY option, then RMAN conducts all operations on the target database instance specified by the command-line parameter or the instance connected to when you issued the CONNECT command. Typically, you should not use the CONNECT parameter in conjunction with the AUXILIARY option.

NOTE: We can also assign specify an assigned name to channels that you allocate when using the allocate channel command. For example the following command will create a channel named c1: RMAN> run {... allocate channel c1 device type disk; ...}

NOTE: If AUXILIARY is specified, then this configuration is used only for channels allocated at the auxiliary instance. If no auxiliary device configuration is specified, and if RMAN needs to automatically allocate auxiliary channels, then RMAN uses the target database device configuration. It is not necessary to specify configuration information for auxiliary channels unless they require different parameters from the target channels.

NOTE: For generic channels of a specified device type, a new command erases previous settings for this device type. Assume that you run these commands: CONFIGURE CHANNEL DEVICE TYPE sbt MAXPIECESIZE 1G; CONFIGURE CHANNEL DEVICE TYPE sbt RATE 1700K; The second command erases the MAXPIECESIZE setting of the first command.

NOTE: It is useful to understand how the CLEAR command works for this parameter. CLEAR Clears the specified channel. For example, CONFIGURE CHANNEL 1 DEVICE TYPE DISK CLEAR returns only channel 1 to its default, whereas CONFIGURE CHANNEL DEVICE TYPE DISK CLEAR returns the generic disk channel to its default. Note that you cannot specify any other channel options (for example, PARMS) when you specify CLEAR.

Here is the general syntax:

    CONFIGURE MAXSETSIZE TO { integer [K|M|G] | UNLIMITED | CLEAR };

        TO integer       Specifies the maximum set size in bytes, kilobytes (K),
                         megabytes (M), or gigabtyes (G). The default setting is
                         in bytes and is rounded down to kilobtyes. For example,
                         if you set MAXSETSIZE to 5000, RMAN sets the maximum set
                         size at 4 kilobytes (that is, 4096 bytes), which is the
                         lower kilobyte boundary of 5000. The minimum value must
                         be greater than or equal to the database block size.
        TO UNLIMITED     Specifies that there is no size limit for backup sets.
        CLEAR            Resets the maximum set size to its default value.

The following command will set the maximum size of a backup set to 1.5GB:

RMAN> CONFIGURE MAXSETSIZE TO 1500m;

RMAN-06183: datafile or datafilecopy larger than SETSIZE: file# 1 /u10/app/oradata/TARGDB/users01.dbf

If you want to set the value backup to its default, use:

RMAN> CONFIGURE MAXSETSIZE CLEAR;

To set the snapshot control file to a different location (and name) use the following:

RMAN> CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/orabackup/rman/ORA920/scontrolfile.ctl';

NOTE: The default value for the snapshot control file name is platform-specific and dependent on the Oracle home. For example, the default on some UNIX system is ?/dbs/snapcf_@.f. If you clear the control file name, and you change the Oracle home, then the default location of the snapshot control file changes as well.

The exclusion is stored as an attribute of the tablespace, not the individual datafiles, so the exclusion applies to any files that are added to this tablespace in the future.

If you run CONFIGURE ... CLEAR on a tablespace after excluding it, then it returns to the default configuration of "not excluded."

You can still back up the configured tablespace by explicitly specifying it in a BACKUP command or by specifying the NOEXCLUDE option on a BACKUP DATABASE command.

The general syntax is:

EXCLUDE FOR TABLESPACE tablespace_name;

RMAN> CONFIGURE EXCLUDE FOR TABLESPACE READ_ONLY_TBS;