RMAN Configuration Demystified: A Practical Deep Dive for DBAs – Part 3

RMAN Configuration Demystified: A Practical Deep Dive for DBAs – Part 3

LIST Commands:-

Command Description LIST BACKUP OF DATABASE; Lists all backup sets (full, incremental, archivelogs) related to the entire database. LIST COPY OF DATAFILE 1, 2; Lists image copies of datafiles 1 and 2. These are exact file copies, not in backup set format. LIST BACKUP OF ARCHIVELOG FROM SEQUENCE 10; Shows archive log backups starting from sequence 10 onward. LIST BACKUPSET OF DATAFILE 1; Lists backup sets that include datafile 1. LIST BACKUP; Shows all backup sets and image copies in the RMAN catalog/control file. LIST COPY; Lists all image copies (of datafiles, control files, etc.). LIST ARCHIVELOG ALL; Lists all archived redo logs known to RMAN (including backed-up or not). LIST RESTORE POINT <Restore_point_name>; Lists a specific restore points details. Useful for point-in-time recovery. LIST RESTORE POINT ALL; Lists all restore points in database. LIST EXPIRED BACKUP; Lists expired backups (files not found on disk, marked expired by RMAN). LIST BACKUP SUMMARY; Provides a summary view (high-level) of backup sets — size, date, device type, etc. LIST BACKUPSET TAG 'weekly_full_db_backup'; Lists backup sets with a specific tag (e.g., full weekly backups). LIST BACKUPSET 213; Displays information about backupset with ID 213. LIST COPY OF DATAFILE 2 COMPLETED BETWEEN '10-DEC-2024' AND '17-DEC-2024'; Shows image copies of datafile 2 completed within a date range. LIST BACKUP OF DATAFILE 1; Lists backups that include only datafile 1.

REPORT Commands:-

Command	Description
REPORT OBSOLETE;	Lists backups that are no longer needed according to current retention policy (can be deleted).
REPORT SCHEMA;	Displays the current database schema as seen by RMAN (tablespaces, datafiles).
REPORT NEED BACKUP;	Shows files that need a backup based on the retention policy.
REPORT NEED BACKUP RECOVERY WINDOW OF 2 DAYS DATABASE DEVICE TYPE SBT;	Reports files that need a backup to satisfy a 2-day recovery window for tape.
REPORT NEED BACKUP DEVICE TYPE DISK;	Same as above, but for disk-based backups.
REPORT NEED BACKUP TABLESPACE USERS DEVICE TYPE SBT;	Shows if tablespace USERS needs backup on tape.
REPORT OBSOLETE RECOVERY WINDOW OF 3 DAYS;	Lists backups that fall outside a 3-day recovery window — can be purged.
REPORT OBSOLETE REDUNDANCY 1;	Lists backups that exceed a redundancy of 1 copy, meaning you can safely delete extras.

CROSSCHECK Commands:-

Command	Description
CROSSCHECK BACKUP DEVICE TYPE DISK;	Checks all disk-based backups to ensure the files still exist on disk.
CROSSCHECK BACKUP DEVICE TYPE SBT;	Checks tape-based (SBT) backups for availability.
CROSSCHECK BACKUP;	Validates all backups: backup sets, image copies, proxy copies — regardless of device type.
CROSSCHECK COPY OF DATABASE;	Validates all image copies of the entire database (datafiles, controlfiles, etc.).
CROSSCHECK BACKUPSET 1338, 1339, 1340;	Checks specific backup sets by ID numbers.
CROSSCHECK BACKUPPIECE TAG nightly_backup;	Checks all backup pieces that were tagged with nightly_backup.
CROSSCHECK BACKUP OF ARCHIVELOG ALL SPFILE;	Verifies backups of all archivelogs and SPFILEs.
CROSSCHECK CONTROLFILECOPY '/tmp/control01.ctl';	Checks the availability of a control file copy at a specific location.

DELETE Commands:-

Command Description DELETE BACKUPPIECE 101; Deletes the specific backup piece with ID 101 from disk or tape. DELETE CONTROLFILECOPY '/tmp/control01.ctl'; Deletes a control file copy located at /tmp/control01.ctl. DELETE NOPROMPT ARCHIVELOG UNTIL SEQUENCE 300; Deletes all archived redo logs up to sequence 299, without prompting for confirmation. Useful for space management. DELETE BACKUP TAG 'before_upgrade'; Deletes all backups (sets or copies) with the tag before_upgrade. Helpful in identifying backups made for specific events. DELETE ARCHIVELOG ALL BACKED UP 3 TIMES TO SBT; Deletes all archived logs that have been successfully backed up 3 times to tape (SBT). Ensures recoverability is retained before deletion. DELETE EXPIRED BACKUP; Deletes all expired backups (files that were marked as EXPIRED after a CROSSCHECK operation). DELETE OBSOLETE; Deletes all backups (datafile, archivelog, controlfile, etc.) no longer needed according to the configured retention policy (either redundancy or recovery window).

RMAN Configuration Demystified: A Practical Deep Dive for DBAs – Part 2

 

RMAN Configuration Demystified: A Practical Deep Dive for DBAs – Part 2

 

RMAN > CONFIGURE DEVICE TYPE DISK PARALLELISM 2;

 

• RMAN opens 2 channels to write to disk simultaneously.
• This improves backup/restore speed, especially for large databases or multiple datafiles.
• Each channel can operate independently, writing to different backup pieces.

 

RMAN >CONFIGURE DEVICE TYPE SBT PARALLELISM 2;

 

·         RMAN will use 2 channels to send backup data to tape drives in parallel.

·         This improves throughput (faster backups/restores) especially when:

·         You have multiple tape drives.

·         Your tape infrastructure supports concurrent streams.

 

RMAN >CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT '/backup/orabackup/ora_df%t_s%s_s%p';

 

·         Sets the backup file naming format for disk backups.

·         %t represents four byte time stamp, %s with the backup set number, and %p with the backup piece number.

 

RMAN >CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 2G;

 

·         RMAN Limits maximum size of a backup piece to 2 GB.

 

RMAN >CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT ‘/tmp/%U’;

 

·         Overrides previous disk format to /tmp/%U. (%U = unique filename)

 

RMAN >CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT ‘/disk1/%U’, ‘/disk2/%U’;

 

Defines where and how RMAN should name the backup files:

• %U is a substitution variable that generates a unique file name.
• RMAN will alternate writing backup pieces between /disk1/ and /disk2/ paths.
• This provides load balancing across multiple directories/disks.

 

RMAN >CONFIGURE DEVICE TYPE <DISK | SBT> BACKUP TYPE TO COMPRESSED BACKUPSET;

 

This Configures RMAN to always create compressed backup sets instead of regular backup sets or image copies.

 

RMAN >CONFIGURE CONTROLFILE AUTOBACKUP ON;

 

This is used to enable automatic backup of the control file and the server parameter file (SPFILE) every time an RMAN backup is run or a structural change is made to the database.

 

RMAN >CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/u01/orclbackup/ora_cf%F';

 

This sets a custom format for automatic control file and SPFILE backups when the device type is DISK.

%F Combines the DBID, day, month, year, and sequence into a unique and repeatable generated name

 

RMAN >CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '+DATA/%F';

 

This is used to configure automatic control file and SPFILE backups to be stored in an Oracle ASM disk group named +DATA

 

RMAN >CONFIGURE BACKUP OPTIMIZATION ON;

 

It enables backup optimization, which helps avoid backing up files that haven't changed since the last backup.

With BACKUP OPTIMIZATION ON, RMAN will skip backing up:

• Datafiles that are:
• part of a previous backup of the same file
• not changed since that backup
• Archived redo logs that were already backed up to the same device type
• Control files and SPFILEs that are unchanged

RMAN >CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE SBT TO 2;

 

·         This command instructs RMAN to create 2 identical copies of each datafile backup when backing up to SBT (tape).

·         It will write 2 separate backup sets, each containing the same datafiles.

·         This increases redundancy — useful for offsite + onsite storage, or general fault tolerance.

 

RMAN >CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE SBT TO 2;

 

·         This tells RMAN to create 2 identical copies of each archived redo log backup when backing up to SBT (tape).

·         It writes them as separate backup sets (not just duplicated files in the same set)

 

RMAN >CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2;

 

·         It configures RMAN to create 2 identical backup copies of each datafile when backing up to disk.

·         Each copy is a complete, usable backup of the datafile.

·         This provides redundancy in case one backup file is lost or corrupted.

 

RMAN Configuration Demystified: A Practical Deep Dive for DBAs – Part 1

 

RMAN Configuration Demystified: A Practical Deep Dive for DBAs – Part 1

 

rman TARGET SYS/target_pwd@target_str

 

Explanation:

• This command starts RMAN and connects only to the target database, using the credentials provided.
• Since there's no CATALOG clause, this is a NOCATALOG mode backup/restore operation.
• target_pwd is the password of the SYS user, and target_str is the TNS alias (or connection string) of the target database.

Use Case:

Used for RMAN operations without a recovery catalog. The control file is used to store backup metadata.

 

rman TARGET / CATALOG rman/rman@rcat

 

Explanation:

• Connects to the target database using OS authentication (TARGET /) — assuming the user has SYSDBA privilege.
• Connects to the recovery catalog database using the user rman with password rman and TNS alias rcat.

Use Case:

Used when backup metadata is maintained in a Recovery Catalog (preferred for environments with multiple databases or long backup retention policies).

 

rman TARGET / CATALOG rman/rman@rcat AUXILIARY sys/aux_pwd@aux_str

 

First let’s crack what is TARGET , CATALOG and AUXILIARY

TARGET Database :

This is the main database you want to back up, restore, or recover.

It is the primary subject of all RMAN operations.

You must always connect to a target database, even if using a recovery catalog.

E.g.

rman TARGET sys/password@orcl

rman TARGET /

 

CATALOG Database(Recovery Catalog)  :

The Recovery Catalog is an optional separate database schema (often in a dedicated database) that stores RMAN metadata.

It offers more advanced reporting, longer metadata retention, and can manage multiple target databases.

E.g.

rman TARGET / CATALOG rman/rman@rcat

rman/rman@rcat is the connection to the Recovery Catalog stored in the rcat database.

 

AUXILIARY Database:

The AUXILIARY is a secondary or temporary database used for specific RMAN operations

E.g.

rman TARGET / CATALOG rman/rman@rcat AUXILIARY sys/aux_pwd@aux_str

 

Explanation:

• Connects to:
• TARGET database via OS authentication.
• CATALOG database using rman user.
• AUXILIARY database using SYS user with password aux_pwd and TNS alias aux_str.

Use Case:

Used for operations that involve a secondary (auxiliary) database, such as:

• Duplicating a database (cloning).
• Tablespace point-in-time recovery (TSPITR).
• Database point-in-time recovery (DBPITR).
• Restore and recovery to an alternate location.

 

RMAN >CONFIGURE CHANNEL DEVICE TYPE sbt CLEAR;

 

• Clears any custom channel configuration for SBT (tape) backups.

 

RMAN >CONFIGURE RETENTION POLICY CLEAR;

 

• Removes the existing retention policy setting.

 

RMAN >CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK CLEAR;

 

·         Clears the control file autobackup format setting for disk.

 

RMAN >CONFIGURE DEFAULT DEVICE TYPE TO DISK/SBT;

 

·         Sets the default device for RMAN backups.

·         DISK: Backups go to file system.

·         SBT: Backups go to tape (e.g., via third-party software like NetBackup).

 

RMAN >CONFIGURE RETENTION POLICY TO REDUNDANCY 3;

 

·         Redundancy in RMAN means how many copies of a distinct backup RMAN should retain at minimum.

·         When you set REDUNDANCY 3, you're telling RMAN:

"Keep at least 3 full backups of each datafile. If there are more than 3, the older ones can be marked obsolete."

RMAN >CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 4 DAYS;

 

·         RMAN will retain all backup sets (datafiles, control files, archived logs, etc.) that are required to perform a point-in-time recovery to any time in the last 4 days.

·         Older backups beyond the 4-day window are considered obsolete and can be deleted.