Rman

Introduction to

Recovery Manager

®

April 21, 2023

Backup & Recovery Utility

Oracle Corporation

April 21, 2023 Recovery Manager - 2

What is Recovery Manager

• Recovery Manager is a tool that:• manages the process of creating backups, and also manages the process of

restoring and recovering from them.

• directs the Oracle server to back itself up, and restore and recover itself.

• Many features of Recovery Manager are also available through the Oracle Enterprise Manager - Backup Wizard.

• Recovery Manager is a Command Line Interface.


Features

• Automation of Backup, Restore, and Recoverye.g. addition of data file will be automatically detected, and included in the next backup

• Incremental Backups (up to 4 levels. Level 0 and levels 1 to 4)• reduction in size of backup

• better performance during recovery

• possible reduction in time taken to perform backup

• Corrupt block detection during• backup

• v$backup_corruption, v$copy_corruption

• also reported in the database’s alert log and trace files

• restore: reported in RMAN log, as well as target database alert and trace

• Easily manages distributing database backups, restores, and recoveries across clustered nodes in an Oracle Parallel Server/RAC.


Features

• Easy backup of Archived redo logs.

• Performance• Automatic Parallelization of backup, restore, and recovery.

• Multiplexing prevents flooding any one file with reads and writes while still keeping a tape drive streaming.

No generation of extra redo during open database backups (also no worries about the database crashing with files in backup mode).

• Can also limit:• Number of open files, to overcome O/S limits on concurrent files opened.

• Size of backup piece• This is important, as a backup piece size may easily be over the maximum file

size allowed by the Operating System or Media Management software.


Terminology

• Backup SetA logical object, containing backups of one or more datafiles or archived logs. A backup set consists of one or more physical files called backup pieces.

• Backup PieceA file that contains the data for a backup set. If a backup set requires more bytes than can be supported by one file in the underlying media, then the backup set will be written to as many backup pieces as necessary.

• Media ManagerA non-Oracle software product that knows how to manage tape drives, tape libraries, and other types of tertiary storage.


Recovery Manager Components

• Components of Recovery Manager:• Recovery Manager executable (rman)

• Target Database

• Recovery Catalog (or target database’s control file)

• Server Processes (i.e. channels)

• Recovery Manager executable (rman)• Translates Recovery Manager commands entered by the user into a

sequence of steps which operate on physical files.

• Sends the Backup, Restore, and Recovery steps to the target database for execution.

• Coordinates and monitors the execution of these steps.

• Generates steps which update the Recovery Catalog (if a RC is used).


Recovery Manager Architecture

Media Management Server

SGA

server

(default)

server

(polling)

Target

File1

File4

File3

CF

Recovery Manager RecoveryCatalog

SCF

File2

MML

server

server

Recovery Catalog

channelSBT_TAPE


Deciding Whether to Use a Recovery Catalog

• It is possible for Recovery Manager to use just the target database's control file (i.e. without a Recovery Catalog). Implications:+ There is no extra overhead of a Recovery Catalog

- If you lose your control file and need to restore and recover the database, restore and recovery has to be followed in care by following the Metalink Note: 60545.1

- - Stored scripts are not available.

- If the database uses a large number of data files (1000+), then backup and restore performance is better with a recovery catalog.

• If not using a catalog, multiple backups of the control file should be kept in distinct locations (on different disks, tapes and/or machines). These backups must be restorable without Recovery Manager.


Creating a Recovery Catalog

• Choose whether to create a separate database for the Recovery Catalog, or install it in an existing database.• If you decide to create a separate database, then create it using the same

procedures you would to create any Oracle database.

• Note:• Do not install the recovery catalog schema in the target database.

• Do not put the catalog on the same physical disks as the target database.

• Decide whether to create a separate tablespace for the Recovery Catalog.

e.g. To create a separate tablespace, start Server Manager, and:SVRMGR> connect internal

SVRMGR> create tablespace rcvcat

2> datafile ‘/oracle/rcvcat/prod/rcvcat_1.dbf’ size 20m;


Creating a Recovery Catalog

• Create the schema owner (this example assumes there is a temp tablespace, and a separate Recovery Catalog tablespace), and grant the required privileges.SVRMGR> connect internal

SVRMGR> create user rman identified by rman

2> temporary tablespace temp

3> default tablespace rcvcat

4> quota unlimited on rcvcat;

SVRMGR> grant recovery_catalog_owner to rman;

• Create the Recovery Catalog Application in the new user:SVRMGR> connect rman/rman

SVRMGR> @?/rdbms/admin/catrman

Create the Recovery Catalog Application in the new user (8i/9i):$ rman catalog rman/rman

RMAN> create catalog


Using a Recovery Catalog

• If you use a Recovery Catalog, you must decide:• How, and how frequently, the Recovery Catalog will be backed up.

Possible backup methods include:• Maintain two or more catalogs, and resync both (or use Replication)

• Use RMAN (switch target db and RC roles, or use no RC), export, or OS utilities

• How to automate Catalog resyncs, and how often• use a utility such as cron to schedule regular resyncs

• resyncs happen automatically with each backup, which may be often enough


Linking with a Media Manager

• To be able to write to sequential devices such as Tape, you must link the Oracle server software with software which is written by a Media Management vendor.

• This software (usually known as the Media Management Library, or Media Management Layer) is called by Oracle when Oracle needs to write to, or read from devices supported by the Media Manager.

• An example of linking Oracle on Solaris, with an MML (the MML is libobk.so, and is located in /usr/lib):

Shutdown all databases using that executable set before linking, then:$ cd $ORACLE_HOME/lib

$ mv libobk.so libobk.so.orig #if libobk.so already exists, rename it

$ ln -s /usr/lib/libobk.so .

$ cd $ORACLE_HOME/rdbms/lib

$ make -f ins_rdbms.mk ioracle

• In 8.1.5, no link is needed to install a media manager. Just point the symbolic link $ORACLE_HOME/lib/libobk.so to your MML library, and re-start the Oracle instance.


Starting Recovery Manager

• There are a number of ways to start Recovery Manager, depending on how you have configured it. Below are a few examples:

• Connecting to a local target instance • Without a Recovery Catalog, without specifying a username/password

$ setenv ORACLE_SID prod

$ rman nocatalog

RMAN> connect target #connects to SYS using SYSOPER

• Without a Recovery Catalog, if user SCOTT has SYSDBA or SYSOPER$ setenv ORACLE_SID prod

$ rman target scott/tiger nocatalog

• Using a Recovery Catalog$ setenv ORACLE_SID prod

$ rman rcvcat rman/rman@rcat

RMAN> connect target #connects to SYS using SYSOPER


Starting Recovery Manager

• Connecting to a target instance (either locally or remotely) when using a password file, and specifying a TNS alias in the target connect string:• Without a Recovery Catalog:

$ rman target internal/secret@prod nocatalog

• Without a Recovery Catalog, if SCOTT has SYSDBA or SYSOPER$ rman target scott/tiger@prod nocatalog

• Using a Recovery Catalog

$ rman target internal/secret@prod rcvcat rman/rman@rcat


Registering a Database in a Recovery Catalog

• If using a Recovery Catalog, before you use Recovery Manager to perform any backups, you must register the database with the Recovery Catalog. The target database you connect to will be the database registered in the catalog.RMAN> register database;

• The register database command identifies the database to the Recovery Catalog.• All information about the target database’s structure is propagated to the

Recovery Catalog from the target database’s control file.

• The database must be mounted or open to perform this action.


Backup Overview

• The database can be Open or Closed during backup• If you are performing a closed backup, the database must be mounted, but

not open.SVRMGR> shutdown immediateSVRMGR> startup mount

• If you are performing a backup while the database is open, the tablespaces should not be put in ‘hot backup’ mode (i.e. you should not issue an ‘alter tablespace begin backup’ command).

• Recovery Manager allows you to backup the whole database, or any of the following subsets, whether the database is open or closed (of course, as in v7, the database must be in archivelog mode to take an open backup):

• database• tablespace(s)• datafile(s) and datafile copies• control file, spfile

• Archived logs may also be backed up


Backup Overview

• Backup Tags• Backups can be given a 30 character name called a Tag:

• weekly_full

• daily_incremental

• Tags do not need to be unique.

• Restore can override automatic backup selection by specifying a tag.


Types of Backups

• There are two types of Recovery Manager backups:• File Copies

• Backup Sets

• Recovery Manager automatically propagates changes in database structure information to the Recovery Catalog (from the control file) before executing certain commands (e.g. backup)• The information propagated includes new datafiles, resized datafiles,

dropped tablespaces, new archivelogs


File Copy

• A File Copy is created by the copy command and• Is an exact image copy of the original file

• Contains only a single input file (datafile, archivelog or controlfile)

• Is most like an Operating System backup (contains all blocks)

• Can be a part of an incremental strategy; but a file copy always includes all blocks, and hence can only be a level 0

run {

allocate channel d1 type disk;

copy

level 0

datafile 1 to ‘/oracle/prod/backup/file1.dbf’;

}


Parallelization of File Copies

• Parallelization of File Copies is achieved by copying multiple files within one copy command, as well as allocating multiple channels.run {





copy #first <- RMAN comment

datafile 1 to ‘/oracle/backup/prod1/d1/prd1.dbf’,

datafile 2 to ‘/oracle/backup/prod1/d2/prd2.dbf’,

datafile 3 to ‘/oracle/backup/prod1/d3/prd2.dbf’;

copy #second

datafile 4 to ‘/oracle/backup/prod1/d4/prd3.dbf’;

sql ‘alter system archive log current’; }


Backup Set

• A Backup Set is created by the backup command and• Usually contains multiple source files (multiplexed in the output)

• It is a logical entity, comprising one or more physical output files called backup pieces

• Can be written to disk or ‘sbt_tape’

• A restore operation is required to extract files from a backup set

• There are two types of Backup Sets• Datafile backup sets (can include control files)

• Archivelog backup sets (can only contain archivelogs)

• Datafile backup sets• Can be Incremental or Full (are full, by default)

• Do not include empty blocks


Backup Pieces

• A Backup Set is a logical entity which is composed of one or more physical output files, called backup pieces

• A backup set usually has only one backup piece.• When using ‘sbt_tape’ the only time a backup set has more than one piece

is when the maximum piece size is limited by the user:

e.g. Tablespace backup to one tape drive, max. file size is 4Gbrun {

allocate channel t1 type ‘SBT_TAPE’;

set limit channel t1 kbytes 4194304;

backup format ‘df_%t_%s_%p’ tablespace user_data;

}

If the output is < 4Gb, only one backup piece will be written. If the output size is > 4Gb, more than one backup piece will be written. Each backup piece will have blocks from all files belonging to the tablespace interspersed together.

• In 8i, the media management layer can inform rman of its maximum backup piece size, which may cause multiple pieces to be created.


Incremental Datafile Backup

• Is a backup of a datafile which only copies out Oracle blocks which have been modified since a previous incremental:• An incremental backup at level N (where N > 0) backs up all blocks

modified since the previous incremental at a level < N-1

• Are initially based on a Level 0 backup set, or a Level 0 File Copy

• Can be faster than performing full (or level 0) backups

• Write out fewer blocks than full (or level 0) backups

• Are by default non-cumulative

• Available only with Enterprise Edition

changedblocks

Level 0 2 2 1 2 2 2 0Day Sun Mon Tue Wed Thu Fri Sat Sun

all non-emptyblocks


Cumulative Incremental Backups

• A cumulative incremental backup at level N (where N > 0) backs up all blocks modified since the previous incremental at a level <= N

• Are provided for recovery speed

• Because cumulative Incrementals backup blocks previously backed up at the same level:• They may take longer and will write more blocks than non-cumulative.

• Fewer backups at each level must be applied when recovering.

changedblocks

Level 0 2 2C 1 2 2C 2C 0Day Sun Mon Tue Wed Thu Fri Sat Sun

all non-emptyblocks


Archivelog Backup Sets• Only include archivelogs

• Are always full backups

• As Recovery Manager has access to control file information, it knows which logs have been archived.

This prevents a common problem experienced by users, of not knowing whether an archive log has been completely copied out to the archive log destination before attempting to back it up.

Example:run {



backup format ‘al_%t_%s_%p’ archivelog all delete input;

}

As with datafile backup sets, archivelog backups are automatically distributed across the number of channels specified.


Archivelog Backup Sets

• Archivelogs may be specified for backup in many different ways:• by log sequence:

backup archivelog low logseq 20 high logseq 50 thread 1;

• by SCN:backup archivelog from scn 1 until scn 9999999;

• by time:backup archivelog from time ‘01-jan-98’ until time ‘30-jun-98’;

• by name:backup archivelog like ‘/oracle/arc/dest/log%’;

• all archived logs:backup archivelog all;

• The ‘delete input’ option can be used to delete logs from disk after they have been successfully backed up.


Restore Concepts

• To reconstruct, or bring back an original file from backup.• Recovery Manager allows you to restore any logical unit of a

database:• database restore database;

• tablespace restore tablespace <name>,..,<name>;

• datafile restore datafile <name>,..,<name>;

• control file restore controlfile to <location>;

restore controlfile; The controlfile will automatically be restored to all locations specified in the init.ora file (i.e. replicate controlfile will not be needed).

• Archived logs may also be manually restored. Usually this is not needed, as Recovery Manager automatically restores all archivelogs which are needed during the Recovery phase. Use SET ARCHIVELOG DESTINATION to override the target database's LOG_ARCHIVE_DEST setting.restore archivelog [all|like <filename>|<archivelog range>| etc…);


Restore Concepts

• Recovery Manager:• Queries the Recovery Catalog to determine the configuration of the

database, and to find out what backups are available for use.• Decides which backups are the optimal ones to use to restore the specified

files.

• When compiling lists of files to restore, Recovery Manager takes into consideration:

• Time Specifications (e.g. for a Point-In-Time Restore)• Any tags specified by users• The channel type (disk/’sbt_tape’) allocated. To ensure Recovery Manager

will find the most recent backups, allocate the appropriate channel type.• The ‘from backupset/datafilecopy’ option, if specified.• Note that Datafile Copies do not need to be restored, they can be used in-

situ by executing a ‘switch’ command, which directs the database to use this file as the actual file in the database.


Restore Example

• Restore the whole database, including control file (to each file’s original location).

As the whole database and control file are being restored, the database should be started, but not mounted.

Start Server Manager, then:SVRMGR> shutdown immediate

SVRMGR> startup nomount


Restore Example

Then start Recovery Manager:rman target internal/secret@prod rcvcat rman/rman@rcatRMAN> run {2> allocate channel t1 type ‘sbt_tape’;3> restore controlfile to ‘/tmp/cf’;4> replicate controlfile from ‘/tmp/cf’;5> sql ‘alter database mount’;6> restore database;7> }

The database has been restored If the backup is consistent, and the DBA either does not want to, or cannot perform recovery, the database can be opened resetlogs, by adding the sql below to the script (a fake recovery is not required):sql ‘alter database open resetlogs’;


Recovery Concepts

• Recovery is the process of using redo logs to ‘re-play’ database changes to datafiles, to make the files current after they have been restored from a backup.

• If the database is in ARCHIVELOG mode, it is possible to either completely recover the database, or recover the database to any arbitrary point-in-time (incomplete recovery).

• For NOARCHIVELOG mode databases, recovery is not usually possible. The only option is to restore from a consistent whole database backup.

• If a database is closed during recovery, all files in that database must be consistent with each other before the database can be opened.

• If a database is open during a tablespace or datafile recovery, the tablespace or datafile must be consistent with the remaining datafiles before it can be brought online (implying that incomplete recovery is not possible in this scenario).


Phases of RMAN Recovery

• Recovery Manager performs recovery in 4 phases:• If a controlfile was restored, repair it.

• Apply any incremental backups that can make the files newer.(Incremental backups are applied to a level 0 or full)

• Apply redo which is currently on disk.

• If all redo required for recovery is not on disk, restore archivelogs, then apply them and any redo in the online redo logs needed for recovery.


Tablespace Recovery: Example

• This example shows the restoration and recovery of all files in the user_data tablespace.

Assume the database is open.$ rman target internal/secret@prod rcvcat rman/rman@rcat

RMAN> run {

2> allocate channel t1 type ‘sbt_tape’;

3> sql ‘alter tablespace user_data offline immediate’;

4> restore tablespace user_data;

5> recover tablespace user_data;

6> sql ‘alter tablespace user_data online’;

7> }

• The tablespace is now available for use.


Point-In-Time Recovery: Example

• Restore the whole database, including control file (to the original locations) until time '1998/02/23 16:00:00'.SVRMGR> shutdown abort

SVRMGR> startup nomount

$ rman target internal/secret@prod rcvcat rman/rman@rcat

RMAN> run {

2> set until time "to_date('1998/02/23 16:00:00',

3> 'YYYY/MM/DD HH14:MI:SS')";

4> allocate channel t1 type 'SBT_TAPE';

5> restore controlfile to '/tmp/cf';

6> replicate controlfile from '/tmp/cf';

7> sql 'alter database mount';

8> restore database;

9> recover database;

10> }

• In 8i, the shutdown and startup commands can be done from RMAN.


Catalog Maintenance Commands

• The CHANGE command is used to update the availability information in the Recovery Catalog:

• To mark a backup piece, file copy or archivelog as unavailable or available for restore or recovery:RMAN> change archivelog

2> '/disk1/archivelog/al_prd1_123.rdo' unavailable;

• To delete a backup piece, file copy or archivelog which is no longer required from the controlfile, recovery catalog, and from the media it resides on:RMAN> allocate channel t1 for delete type 'sbt_tape';

RMAN> change backuppiece <key> delete;

The keys are determined by using the ‘list’ command. The 'allocate channel … for delete' command is required when using the 'change … delete' or 'crosscheck' commands.

• To remove references to a backup piece, file copy or archivelog from the recovery catalog (e.g. if it was deleted by an O/S utility):RMAN> change archivelog2> ‘/disk1/archivelog/al_prd1_123.rdo’ uncatalog;



• If the DBA has deleted a large number of files on disk (e.g. archived logs), a more efficient method of reconciling the Recovery Catalog (and controlfile) with what is on disk, is to use ‘change … validate’RMAN> change archivelog all validate; - catalog/uncatalog

RMAN> change archivelog all crosscheck; - available/unavailable

This verifies that the files the Recovery Catalog believes are on disk, are there. If they are not there, these files are identified as deleted in the catalog.



• New for 8i is the 'crosscheck' command, which synchronizes backup pieces in the recovery catalog with their real-world files.RMAN> allocate channel for maintenance type 'sbt_tape';

RMAN> crosscheck backup;

• Use the DELETE EXPIRED BACKUP command to change all EXPIRED backups to DELETED.



• The catalog command:• If there are archivelogs, datafiles copies etc. on disk which were created

before Recovery Manager was used, it is possible to identify the existence of these to the Recovery Catalog:RMAN> catalog archivelog '/disk1/archivelog/al_prd1_1234.rdo';


Dropping the Recovery Catalog

• In 8.0:SVRMGR> connect rman/rman@rcatSVRMGR> @?/rdbms/admin/catnormn

• In 8i:$ rman catalog rman/rman@rcatRMAN> drop catalogThe 'drop catalog' command must be entered twice to confirm that is what you really want to do. All backups for all target databases managed by this catalog will become unusable.


Running Recovery Manager commands

• The commands can also be stored in the Recovery Catalog, with a name. It is then called a Stored Script.

A stored script is only associated with one target database.RMAN> create script alloc_channels {

2> allocate channel c1 type 'sbt_tape';




6> }

To execute the stored script:RMAN> run {

2> execute script alloc_channels;

3> backup database;

4> }


List Command

• Displays the contents of the controlfile or recovery catalog:• All databases known to the recovery catalog or incarnations of a database

RMAN> list incarnation of database;

• Backup Sets or File Copies containing a backup of a specified list of filesRMAN> list backupset of datafile 2;RMAN> list backupset of datafile ‘/d3/dbf/user_prd1.dbf’;

• Backup Sets or File Copies containing a backup of any datafile which is a member of a list of tablespacesRMAN> list copy of tablespace system;

• Backup Sets or File Copies of the whole database, optionally restricted by time, datafile copy name, device name and tag

• Backup Sets containing Archivelogs restricted by name, or by range. For example, list which backup sets contain archivelogs between the sequence 123 and 145RMAN> list backupset of archivelog 2> from logseq 123 until logseq 145 thread 1;


Report Command

• Analyzes the content of the recovery catalog in more detail than list

• Produces reports which can answer questions such as:• What files need a backup?

report need backup

• What files are not recoverable due to unrecoverable operations?

report unrecoverable

• What backups can be deleted (.e. are obsolete)?

report obsolete

• What was the physical schema of the database at a previous point-in-time?

report schema


Report Command

• report need backup and report unrecoverable should be used on a regular basis to ensure:• Recovery is possible

RMAN> report unrecoverable;

• Recovery is possible within an acceptable time

For Example, the following command reports all datafiles which would require the application of 3 or more incrementals to be recovered to their current state

RMAN> report need backup incremental 3 database;

The following command reports all datafiles belonging to the SYSTEM tablespace that haven’t had a backup (full or incremental) in 5 days or more.

RMAN> report need backup days 5 tablespace system;


Duplicate Database

• New command in 8i, DUPLICATE DATABASE, creates a duplicate copy of the target database:• restores backups to a second instance, on the same or a different machine

• recovers those backups to any desired point in time

• sets a new DBID in the duplicated database

• opens the database resetlogs

• You must first create a second instance: net config files, init.ora.This is called the AUXILIARY instance. It should be started, but not mounted, before using the DUPLICATE command. The auxiliary instance does not have to be on the same machine as the target.

• If the duplicate database is on the same machine as the target, the filenames must be changed to avoid conflict with the target database files.

• Syntax: DUPLICATE TARGET DATABASE TO <newdbname>


Tablespace Point-In-Time Recovery

• Can recover one or more tablespaces to an earlier point in time. Typically used to recover from user error.

• Can be done without RMAN, but is complicated, and automated by RMAN.

• Requires an auxiliary instance, which must be on the same machine as the target.

• See the new TSPITR chapter of the 8i Backup and Recovery guide.


Media Manager Problems

• sbtio.log• This is the trace file which your media management product may use to

write debugging/trace information

• can be found in the location specified by user_dump_dest (or by default on Unix systems in $ORACLE_HOME/rdbms/log)


Questions

Documents

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