Tài liệu Oracle® Database Recovery Manager Quick Start Guide doc

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backups on disk as space permits. This minimizes restores from tape during
data recovery operations to shorten restore and recovery times.
About the Recovery Catalog
In addition to RMAN repository records, the recovery catalog can also hold
RMAN stored scripts, sequences of RMAN commands for common backup
tasks. Centralized storage of scripts in the recovery catalog can be more
convenient than working with command files.
Except for stored scripts, all of RMAN’s features work equally well with or
without a recovery catalog. For more information on the recovery catalog
see Oracle Database Backup and Recovery Advanced User's Guide.
About Media Managers
To access sequential media devices like tape libraries, RMAN uses
third-party media management software. A media manager controls these
devices during backup and recovery, managing the loading, labeling and
unloading of media, among other functions. Oracle Corporation’s Backup
Solutions Program (BSP) works with vendors to help them produce media
management software for their devices. For enterprises that already use
media management software in their enterprise, many of those software
products can be directly integrated with RMAN. Contact your media
management software vendor for details about whether they participate in
the BSP and have an RMAN-compatible media management layer.
Starting and Exiting RMAN
The RMAN client is started by issuing the rman command at the command
prompt of your operating system.
RMAN must connect to a target database (with SYSDBA privileges) to
perform backup and recovery tasks. RMAN can also connect to a recovery
catalog database if you are using one. Specify target and recovery catalog
databases using command line options or using the CONNECT command.
This command connects RMAN to a target database and a recovery catalog:
% rman TARGET / CATALOG cat_usr/pwd@cat_str
Connect to a target database without using a recovery catalog:
% rman TARGET SYS/pwd@target_str
Starting RMAN without connecting to a database
% rman
Once started, RMAN displays an "RMAN>" prompt for your commands.
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Syntax of Common RMAN Command-line Options
RMAN
[ TARGET [=] connectStringSpec
| { CATALOG [=] connectStringSpec }
| LOG [=] ['] filename ['] [ APPEND ]
.
.
.
]
connectStringSpec::=
['] [userid] [/ [password]] [@net_service_name] [']
This example appends the output from an RMAN session to a text file at
$ORACLE_HOME/dbs/log/msglog.log
% rman TARGET / LOG $ORACLE_HOME/dbs/log/msglog.log APPEND
To quit the RMAN client, type EXIT at the RMAN prompt:
RMAN> EXIT
Configuring Persistent Settings for the RMAN Environment
You can configure persistent settings in the RMAN environment, which
apply to all subsequent operations, even if you exit and restart RMAN.
Configuring Disk Devices and Channels RMAN channels are connections to
server sessions on the target database, which are used to perform all
backup, restore and recovery operations. By default, RMAN allocates one
disk channel for all operations. You can configure dditional channels for use
with disks and with other media.
By default, RMAN sends all backups to disk. If a flash recovery area is
configured, it is the default destination; otherwise the default directory is
platform-dependent. If, as recommended, you use the flash recovery area
as the destination for all disk backups, you would set up a flash recovery
area and use the following CONFIGURE command:
RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT CLEAR;
The following command configures RMAN to write disk backups to the
/tmp directory:
RMAN> CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT '/tmp/%U';
The format specifier %U is replaced with unique filenames for the files when
you take backups. Refer to Oracle Database Backup and Recovery Advanced
User's Guide. for more details on configuring destinations for your disk
backups.
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Configuring Tape Devices and Channels After configuring your media
management software, you can make the media manager the default
destination for RMAN backups:
RMAN> CONFIGURE DEFAULT DEVICE TYPE TO sbt;
Some media managers require a PARMS string to configure device settings:
RMAN> CONFIGURE CHANNEL DEVICE TYPE sbt PARMS=’ENV=mml_env_settings';
Multiple channels can be configured to run backups in parallel. This
command configures two sbt channels for use in RMAN jobs:
RMAN> CONFIGURE DEVICE TYPE sbt PARALLELISM 2;
Configuring a Retention Policy Retention policy governs how long backup files
are retained. Retention policy can be set in terms of a recovery window
(how far into the past you need to be able to recover your database), or a
redundancy value (how many backups of each file must be retained).
This command ensures that RMAN retains all backups needed to recover
the database to any point in time in the last 7 days:
RMAN> CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS;
This command ensures that RMAN retains three backups of each datafile:
RMAN> CONFIGURE RETENTION POLICY TO REDUNDANCY 3;
Use DELETE OBSOLETE to immediately delete backups no longer required
by the retention policy. (For backups stored in a flash recovery area, you do
not need to perform this step. The database automatically deletes obsolete
files and files already backed up to tape when space is needed.) You can use
the KEEP option of the BACKUP and CHANGE commands to override the
configured retention policy for individual backups for example, to force
the retention of a specific backup.
Configuring Control File Autobackups This command configures RMAN to back
up the control file after each backup or copy:
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP ON;
By default, RMAN automatically names control file autobackups and stores
them in the flash recovery area. The following command configures RMAN
to write control file autobackups to the /mybackupdir directory:
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP FORMAT
FOR DEVICE TYPE DISK TO '/mybackupdir/cf%F';
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The %F element of the format string combines the DBID, day, month, year,
and sequence number to generate a unique filename. %F is required for
control file autobackups.
Restoring Default Values for Configured Settings Reset any CONFIGURE setting to
its default by running the command with the CLEAR option, as shown here:
RMAN> CONFIGURE CHANNEL DEVICE TYPE sbt CLEAR;
RMAN> CONFIGURE RETENTION POLICY CLEAR;
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK
CLEAR;
Viewing Current Settings This command shows all configurable settings:
RMAN> SHOW ALL;
The output lists the CONFIGURE commands to recreate this configuration.
Backing Up Database Files
Use the BACKUP command to back up files. You will usually configure
default devices and channels in advance; BACKUP backs up your data to the
configured default device and channels for the type of backup requested.
If you specify BACKUP AS COPY, then RMAN copies the files as image
copies, bit-for-bit copies of database files that can only be created on disk.
This command creates image copy backups of all datafiles in the database:
RMAN> BACKUP AS COPY DATABASE;
If you specify BACKUP AS BACKUPSET, then RMAN stores its backups in
backup sets. A backup set consists of one or more backup pieces, physical
files containing the data. A backup set usually contains only one backup
piece. Only RMAN can create and restore backup sets. The following
command creates a backup of the database and archived logs on tape, in
backup set format, using the configured channels:
RMAN> BACKUP DEVICE TYPE sbt DATABASE PLUS ARCHIVELOG;
Backing Up Individual Files You can back up individual tablespaces, database
files, server parameter files, and backup sets with various options, as in
these examples:
RMAN> BACKUP ARCHIVELOG COMPLETION TIME BETWEEN
’SYSDATE-31’ AND ’SYSDATE-7’;
RMAN> BACKUP TABLESPACE system, users, tools;
RMAN> BACKUP AS BACKUPSET DATAFILE
’ORACLE_HOME/oradata/trgt/users01.dbf’,
’ORACLE_HOME/oradata/trgt/tools01.dbf’;
RMAN> BACKUP CURRENT CONTROLFILE TO ’/backup/curr_cf.copy’;
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RMAN> BACKUP SPFILE;
RMAN> BACKUP BACKUPSET ALL;
Note that in the above examples you should enter the path to your Oracle
home in place of "
ORACLE_HOME
".
Backup Options Here are some often-used BACKUP command options:
The following BACKUP commands illustrate these options:
RMAN> BACKUP FORMAT='AL_%d/%t/%s/%p' ARCHIVELOG LIKE ’%arc_dest%’;
RMAN> BACKUP TAG ’weekly_full_db_bkup’ DATABASE MAXSETSIZE 10M;
RMAN> BACKUP COPIES 2 DEVICE TYPE sbt BACKUPSET ALL;
Incremental Backups If you specify BACKUP INCREMENTAL, RMAN will
create incremental backups of your database. Incremental backups capture
on a block-by-block basis changes in your database since a previous
incremental backup. The starting point for an incremental backup strategy
is a level 0 incremental backup, which backs up all blocks in the database.
Level 1 incremental backups, taken at regular intervals, contain only
changed blocks since a previous incremental backup. These can be
cumulative (including all blocks changed since the most recent level 0
backup) or differential (including only blocks changed since the most
recent incremental backup, whether it is level 0 or level 1).
Incremental backups are generally smaller and faster to create than full
database backups. Recovery from an incremental backup is faster than
recovery using redo logs alone. During a restore from incremental backup,
the level 0 backup is used as the starting point, then changed blocks are
updated based on level 1 backups where possible to avoid re-applying
changes from redo one at a time. Recovering with incremental backups
requires no additional effort on your part. If incremental backups are
available, RMAN will use them during recovery.
RMAN’s incrementally updated backups feature allows for a more
efficient incremental backup routine. Changes from level 1 backups can be
used to roll forward an image copy level 0 incremental backup, so that it
Parameter Example Explanation
FORMAT FORMAT ’/tmp/%U’ Specifies a location and name for
backup pieces and copies. You must
use substitution variables to generate
unique filenames.
TAG TAG ’monday_bak’ Specifies a user-defined string as a
label for the backup. If you do not
specify a tag, then RMAN assigns a
default tag with the date and time.
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includes all changes as of the SCN at which the level 1 incremental backup
was created. Recovery using the updated level 0 incremental backup is
faster, because all changes from the level 1 incremental backup have already
been applied.
See Oracle Database Backup and Recovery Basics for more details and examples
for incremental backups and incrementally updated backups.
Validating Backups You can run a test RMAN backup that does not generate
any output. Validation confirms that a backup could be run, by confirming
that all database files exist, are in their correct location, and are free of
physical and logical corruption. For example:
RMAN> BACKUP VALIDATE DATABASE ARCHIVELOG ALL;
Restoring and Recovering Database Files
Use the RESTORE and RECOVER commands for RMAN restore and recovery
of physical database files. Restoring datafiles is retrieving them from
backups as needed for a recovery operation. Recovery is the application of
changes from redo logs and incremental backups to a restored datafile, to
bring the datafile to a desired SCN or point in time.
Recovering the Whole Database Use the RESTORE DATABASE and RECOVER
DATABASE commands on the whole database. For example:
RMAN> STARTUP FORCE MOUNT;
RMAN> RESTORE DATABASE;
RMAN> RECOVER DATABASE;
RMAN> ALTER DATABASE OPEN;
Note that the database must not be open when restoring or recovering the
entire database.
Recovering Current Tablespaces Use the RESTORE TABLESPACE and RECOVER
TABLESPACE commands on individual tablespaces when the database is
open. Take the tablespace that needs recovery offline, restore and then
recover the tablespace, and bring the recovered tablespace online. The
following steps recover the users tablespace:
RMAN> SQL 'ALTER TABLESPACE users OFFLINE';
RMAN> RESTORE TABLESPACE users;
RMAN> RECOVER TABLESPACE users;
RMAN> SQL 'ALTER TABLESPACE users ONLINE';
Recovering Current Datafiles Use the RESTORE DATAFILE and RECOVER
DATAFILE commands on individual current datafiles when the database is
open. Take the datafile that needs recovery offline, restore and recover the
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datafile, and bring the datafile online. For example, to restore and recover
datafile 7:
RMAN> SQL 'ALTER DATABASE DATAFILE 7 OFFLINE';
RMAN> RESTORE DATAFILE 7;
RMAN> RECOVER DATAFILE 7;
RMAN> SQL 'ALTER DATABASE DATAFILE 7 ONLINE';
Recovering Individual Data Blocks RMAN can recover individual corrupted
datafile blocks. When RMAN performs a complete scan of a file for a
backup, any corrupted blocks are listed in V$DATABASE_BLOCK_
CORRUPTION. Corruption is usually reported in alert logs, trace files or
results of SQL queries. Use BLOCKRECOVER to repair all corrupted blocks:
RMAN> BLOCKRECOVER CORRUPTION LIST;
You can also recover individual blocks, as shown in this example:
RMAN> BLOCKRECOVER DATAFILE 7 BLOCK 233, 235 DATAFILE 4 BLOCK 101;
Validating Restores You can run a RESTORE VALIDATE operation to
confirm that a restore operation can be performed successfully. RMAN
decides which backup sets, datafile copies, and archived logs are needed for
the operation, and scans them to verify that they are usable. For example:
RMAN> RESTORE DATABASE VALIDATE;
Reporting on RMAN Operations
The RMAN LIST and REPORT commands, generate reports on backup
activities based on the RMAN repository. Use SHOW ALL to display the
current RMAN configuration. You can also query the views described in
"Backup and Recovery Views" on page 25.
Listing Backups Run the LIST BACKUP and LIST COPY commands to
display information about backups and datafile copies listed in the
repository. You can display specific objects, as in the following examples:
RMAN> LIST BACKUP OF DATABASE;
RMAN> LIST COPY OF DATAFILE 1, 2, 3;
RMAN> LIST BACKUP OF ARCHIVELOG FROM SEQUENCE 1437;
RMAN> LIST CONTROLFILECOPY "/tmp/cf.cpy";
RMAN> LIST BACKUPSET OF DATAFILE 1;
For backups, you can control the format of LIST output with these options:
Parameter Example Explanation
BY BACKUP LIST BACKUP OF
DATABASE BY BACKUP
Organizes the output by backup set.
This is the default mode of presentation.
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For both backups and copies you have the following additional options:
Reporting on Database Files and Backups The REPORT command performs more
complex analysis than LIST. Some of the main options are:
Monitoring RMAN Through V$ Views Status information for jobs in progress and
completed jobs is stored in V$RMAN_STATUS. V$RMAN_OUTPUT contains
the text ouptut of all RMAN jobs.
BY FILE LIST BACKUP BY FILE Lists the backups according to which
file was backed up.
SUMMARY LIST BACKUP
SUMMARY
Displays reduced output. By default,
the output is VERBOSE.
Parameter Example Explanation
EXPIRED LIST EXPIRED COPY Displays files inaccessible based
on the CROSSCHECK command.
RECOVERABLE LIST BACKUP RECOVERABLE Specifies datafile backups or
copies that are available and that
can be restored and recovered in
the current database incarnation.
Parameter Example Explanation
NEED BACKUP REPORT NEED BACKUP
DATABASE
Shows which files need backing
up under current retention policy.
Use optional REDUNDANCY and
RECOVERY WINDOW parameters to
specify different criteria.
OBSOLETE REPORT OBSOLETE Lists backups that are obsolete
under the configured retention
policy. Use optional REDUNDANCY
and RECOVERY WINDOW
parameters to specify criteria.
UNRECOVERABLE REPORT UNRECOVERABLE Lists all datafiles for which an
unrecoverable operation has been
performed against an object in the
datafile since the last backup of
the datafile.
SCHEMA REPORT SCHEMA Reports the tablespaces and
datafiles in the database at the
current time (default) or a
different time.
Parameter Example Explanation
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To see status information on jobs in V$RMAN_STATUS use the following
query:
SELECT OPERATION, STATUS, MBYTES_PROCESSED, START_TIME, END_TIME from
V$RMAN_STATUS;
To correlate a channel with a process, run the following query in SQL*Plus
while the RMAN job is executing:
SQL> COLUMN CLIENT_INFO FORMAT a30
SQL> COLUMN SID FORMAT 999
SQL> COLUMN SPID FORMAT 9999
SQL> SELECT s.SID, p.SPID, s.CLIENT_INFO
FROM V$PROCESS p, V$SESSION s
WHERE p.ADDR = s.PADDR
AND CLIENT_INFO LIKE ’rman%’;
To calculate the progress of an RMAN job, run the following query in
SQL*Plus while the RMAN job is executing:
SQL> SELECT SID, SERIAL#, CONTEXT, SOFAR, TOTALWORK,
ROUND(SOFAR/TOTALWORK*100,2) "% COMPLETE"
FROM V$SESSION_LONGOPS
WHERE OPNAME LIKE 'RMAN%' AND OPNAME NOT LIKE '%aggregate%'
AND TOTALWORK != 0 AND SOFAR <> TOTALWORK;
Managing the RMAN Repository
RMAN repository metadata is always stored in the control file of the target
database. You can also create a recovery catalog in a separate database, and
RMAN will record its metadata there as well.
Monitoring Control File Records If you do not use a recovery catalog, then
eventually RMAN control file records are overwritten. Set this initialization
parameter in the parameter file of the target database to determine how
long records are kept:
CONTROL_FILE_RECORD_KEEP_TIME = number_of_days_to_keep
Crosschecking Backups The CROSSCHECK command checks whether RMAN
backups and copies in the repository can still be accessed. Assuming that
you have configured automatic channels, you can run these commands:
RMAN> CROSSCHECK BACKUP; # checks RMAN backups on configured devices
RMAN> CROSSCHECK COPY; # checks RMAN image copies on configured devices
If backups are stored with a media manager and sbt channels are not
configured, then you must allocate a maintenance channel before
CROSSCHECK and DELETE commands on sbt objects:
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RMAN> ALLOCATE CHANNEL FOR MAINTENANCE DEVICE TYPE sbt;
Deleting Backups and Copies The DELETE command removes RMAN backups
and copies from DISK and sbt devices, marks the objects as DELETED in
the control file, and removes the records from the recovery catalog (if you
use a catalog). For example:
RMAN> DELETE BACKUPSET 101, 102, 103;
RMAN> DELETE CONTROLFILECOPY '/tmp/cf.cpy';
RMAN> DELETE NOPROMPT ARCHIVELOG UNTIL SEQUENCE = 7300;
RMAN> DELETE BACKUP OF SPFILE TABLESPACE users DEVICE TYPE sbt;
RMAN> DELETE BACKUP OF DATABASE LIKE '/tmp%'; # pattern match
RMAN> DELETE ARCHIVELOG ALL BACKED UP 2 TIMES TO DEVICE TYPE sbt;
The following options of the DELETE command are also useful:
Cataloging and Uncataloging Backups and Copies The CATALOG command lets
you register information about backups in the RMAN repository, so RMAN
can use it in a restore and recovery operation. A backup will not be listed in
the repository if it was created by an operating-system level file copy, or if it
is older than the CONTROL_FILE_RECORD_KEEP_TIME and is no longer
listed in the RMAN repository. For example:
RMAN> CATALOG DATAFILECOPY '/backup/users01.bak'; # catalogs datafile
copy made at OS level
RMAN> CATALOG LIKE ’/backup’ # catalogs all files in directory
The CHANGE UNCATALOG syntax lets you remove information about
backups and copies from the RMAN repository. If you manually delete a
backup using operating system commands, CHANGE UNCATALOG
updates the repository to reflect that change. For example:
RMAN> CHANGE CONTROLFILECOPY '/tmp/cf.cpy' UNCATALOG;
RMAN> CHANGE BACKUPSET 121,122,127,203,300 UNCATALOG;
Parameter Example Explanation
EXPIRED DELETE EXPIRED Deletes the backups and copies marked as
EXPIRED (that is, "not found") by the
CROSSCHECK command.
OBSOLETE DELETE OBSOLETE Deletes the backups and copies that are
obsolete under the retention policy.
REDUNDANCY and RECOVERY WINDOW
parameters override the configured policy.
NOPROMPT DELETE NOPROMPT
OBSOLETE
Specifies that you do not want to be prompted
to confirm the files to be deleted.