For beginners and non, rman is one of the most obscure Oracle tools, but in reality it is based on quite simple principles. It is true, though, that a restoration can be distructive for a database.
Why is rman dangerous?
rman is dangerous because it works at the database physical level; to understand why, let's say that rman is not "too" different from WinZip. Since everybody knows WinZip, it will probably be easier to understand rman.
Is WinZip dangerous?
The creation of a zip archive is not dangerous, unless you choose the same name for the output file, or the archive is so big that you fill a device or the temporary directory etc. The same thing can be said about rman: taking an rman backup cannot be dangerous (unless you stop the database, or close it intentionally) and you don't overwrite previous backups (you can prevent it).
rman creates a compressed backup of the physical database files, including controlfiles, datafiles, archived logs and stores them somewhere. This somewhere can be a disk (like WinZip) or a tape.
Therefore, the first important point to remember is:
rman creates compressed backups of the physical database; if you prefer, rman zips the database, entirely or not.
Is Unzip dangerous?
Unzip, on the other hand, can be very dangerous. The risk is overwriting files that should not be overwritten and, therefore, losing important content. The very same applies to rman restores: since they overwrite database files, you should know whether this is the right decision because, otherwise, you may lose your data. This is the main difference between an import and an rman restoration:
an rman restoration (restore) overwrites one or more datafiles; this means WATCH OUT.
Our first rman backup
The only requirements for taking simple, useful rman backups are two:
- You database is in archivelog mode
- You have enough disk space somewhere
On our Windows 2000 workstation we open a CMD window and type the following few lines:
E:\>rman target /
Recovery Manager: Release 9.2.0.1.0 - Production
Copyright (c) 1995, 2002, Oracle Corporation. All rights reserved.
connected to target database: ARK9201 (DBID=3564144589)
run {
allocate channel t1 type disk;
backup database format 'E:\RMAN_BACKUPS\ARK9201\%d_%u_%s';
release channel t1;
}
using target database controlfile instead of recovery catalog
allocated channel: t1
channel t1: sid=9 devtype=DISK
Starting backup at 10-DEC-04
channel t1: starting full datafile backupset
channel t1: specifying datafile(s) in backupset
including current SPFILE in backupset
including current controlfile in backupset
released channel: t1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on t1 channel at 12/10/2004 14:28:50
ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode
As we said, the database must be in archive mode if we want to backup open databases. A separate articles explains why it must be so, because it is not so obvious.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 135338868 bytes
Fixed Size 453492 bytes
Variable Size 109051904 bytes
Database Buffers 25165824 bytes
Redo Buffers 667648 bytes
Database mounted.
SQL> alter database archivelog;
Database altered.
SQL> alter database open;
Database altered.
Let's now repeat the operation having put the database in archive mode Choosing C:\Temp as directory for the backup is, of course, a very bad idea. Backups are gold and shoud be kept on a dedicated device; a good name could be E:\RMAN_BACKUPS\SID
E:\>rman target /
Recovery Manager: Release 9.2.0.1.0 - Production
Copyright (c) 1995, 2002, Oracle Corporation. All rights reserved.
connected to target database: ARK9201 (DBID=3564144589)
RMAN> run {
2> allocate channel t1 type disk;
3> backup database format 'E:\RMAN_BACKUPS\ARK9201\%d_%u_%s';
4> release channel t1;
5> }
allocated channel: t1
channel t1: sid=12 devtype=DISK
Starting backup at 26-DEC-04
channel t1: starting full datafile backupset
channel t1: specifying datafile(s) in backupset
including current SPFILE in backupset
including current controlfile in backupset
input datafile fno=00001 name=E:\ORACLE\ORADATA\ARK920\SYSTEM01.DBF
input datafile fno=00002 name=E:\ORACLE\ORADATA\ARK920\UNDOTBS01.DBF
input datafile fno=00004 name=E:\ORACLE\ORADATA\ARK920\EXAMPLE01.DBF
input datafile fno=00009 name=E:\ORACLE\ORADATA\ARK920\XDB01.DBF
input datafile fno=00005 name=E:\ORACLE\ORADATA\ARK920\INDX01.DBF
input datafile fno=00008 name=E:\ORACLE\ORADATA\ARK920\USERS01.DBF
input datafile fno=00003 name=E:\ORACLE\ORADATA\ARK920\DRSYS01.DBF
input datafile fno=00006 name=E:\ORACLE\ORADATA\ARK920\ODM01.DBF
input datafile fno=00007 name=E:\ORACLE\ORADATA\ARK920\TOOLS01.DBF
channel t1: starting piece 1 at 26-DEC-04
channel t1: finished piece 1 at 26-DEC-04
piece handle=E:\RMAN_BACKUPS\ARK9201\ARK920_03G8KC6G_3 comment=NONE
channel t1: backup set complete, elapsed time: 00:25:58
Finished backup at 26-DEC-04
released channel: t1
The resulting backup file(s) are in our case
dir c:\rman_backups\ark9201
Volume in drive C is 80-01-14A2
Volume Serial Number is 64DA-0BF7
Directory of c:\rman_backups\ark9201
12/26/2004 02:29p .
12/26/2004 02:29p ..
12/26/2004 02:44p 418,471,936 ARK920_03G8KC6G_3
Our first archive backup
Taking only the database backup is not enough, for reasons that will be clear later. We must take a backup of the archived log as well, and the command is very similar
RMAN> run {
2> allocate channel t1 type disk;
3> backup archivelog all delete input format 'C:\RMAN_BACKUPS\ARK9201\arch_%d_%u_%s';
4> release channel t1;
5> }
allocated channel: t1
channel t1: sid=12 devtype=DISK
Starting backup at 26-DEC-04
current log archived
channel t1: starting archive log backupset
channel t1: specifying archive log(s) in backup set
input archive log thread=1 sequence=77 recid=1 stamp=545945036
input archive log thread=1 sequence=78 recid=2 stamp=545945039
input archive log thread=1 sequence=79 recid=3 stamp=545945099
channel t1: starting piece 1 at 26-DEC-04
channel t1: finished piece 1 at 26-DEC-04
piece handle=C:\RMAN_BACKUPS\ARK9201\ARCH_ARK920_04G8KTGL_4 comment=NONE
channel t1: backup set complete, elapsed time: 00:00:37
channel t1: deleting archive log(s)
archive log filename=E:\ORA920\RDBMS\ARC00077.001 recid=1 stamp=545945036
archive log filename=E:\ORA920\RDBMS\ARC00078.001 recid=2 stamp=545945039
archive log filename=E:\ORA920\RDBMS\ARC00079.001 recid=3 stamp=545945099
Finished backup at 26-DEC-04
released channel: t1
RMAN>
rman on UNIX
rman works the same way on a UNIX server, using an appropriate directory format:
RMAN> run { allocate channel t1 type disk;
2> backup database format '/u01/oracle/archive/%d_%u_%s';
3> backup current controlfile format '/u01/oracle/archive/%d_%u_%s';
4> release channel t1;}
using target database controlfile instead of recovery catalog
allocated channel: t1
channel t1: sid=26 devtype=DISK
Starting backup at 14:29:22 18-jan-2005
channel t1: starting full datafile backupset
channel t1: specifying datafile(s) in backupset
input datafile fno=00001 name=/u01/oradata/ORA920/system01.dbf
input datafile fno=00002 name=/u02/oradata/ORA920/undo01.dbf
input datafile fno=00004 name=/u01/oradata/OMF_DATA_ORA920/o1_mf_tbs_data_0ybcd28z_.dbf
input datafile fno=00003 name=/u01/oradata/OMF_DATA_ORA920/o1_mf_tools_0ybbwkp7_.dbf
input datafile fno=00005 name=/u01/oradata/ORA920/oem_repository.dbf
channel t1: starting piece 1 at 14:29:24 18-jan-2005
channel t1: finished piece 1 at 14:31:10 18-jan-2005
piece handle=/u01/oracle/archive/ORA920_01gah0q3_1 comment=NONE
channel t1: backup set complete, elapsed time: 00:01:48
Finished backup at 14:31:11 18-jan-2005
Starting backup at 14:31:11 18-jan-2005
channel t1: starting full datafile backupset
channel t1: specifying datafile(s) in backupset
including current controlfile in backupset
channel t1: starting piece 1 at 14:31:15 18-jan-2005
channel t1: finished piece 1 at 14:31:18 18-jan-2005
piece handle=/u01/oracle/archive/ORA920_02gah0th_2 comment=NONE
channel t1: backup set complete, elapsed time: 00:00:05
Finished backup at 14:31:18 18-jan-2005
Starting Control File Autobackup at 14:31:18 18-jan-2005
piece handle=/optware/oracle/9.2.0.1/dbs/c-2554142925-20050118-00 comment=NONE
Finished Control File Autobackup at 14:31:22 18-jan-2005
released channel: t1
RMAN> host ;
oracle@edc-se[on pts/4] ls -ltr /u01/oracle/archive/
total 562128
-rw-r----- 1 oracle dba 282476544 Jan 18 14:31 ORA920_01gah0q3_1
-rw-r----- 1 oracle dba 5177344 Jan 18 14:31 ORA920_02gah0th_2
oracle@edc-se[on pts/4] exit
host command complete
Backup the controlfile
RMAN> run { allocate channel t1 type disk;
2> backup current controlfile format '/u01/oracle/archive/controlf_%d_%u_%s';
3> release channel t1;}
allocated channel: t1
channel t1: sid=26 devtype=DISK
Starting backup at 14:33:59 18-jan-2005
channel t1: starting full datafile backupset
channel t1: specifying datafile(s) in backupset
including current controlfile in backupset
channel t1: starting piece 1 at 14:34:00 18-jan-2005
channel t1: finished piece 1 at 14:34:03 18-jan-2005
piece handle=/u01/oracle/archive/controlf_ORA920_04gah12n_4 comment=NONE
channel t1: backup set complete, elapsed time: 00:00:04
Finished backup at 14:34:03 18-jan-2005
Starting Control File Autobackup at 14:34:03 18-jan-2005
piece handle=/optware/oracle/9.2.0.1/dbs/c-2554142925-20050118-01 comment=NONE
Finished Control File Autobackup at 14:34:07 18-jan-2005
released channel: t1
Here is a backup of archived log files
RMAN> run { allocate channel t1 type disk;
2> backup archivelog all format '/u01/oracle/archive/archive_%d_%u_%s' delete input;
3> release channel t1;}
allocated channel: t1
channel t1: sid=26 devtype=DISK
Starting backup at 14:42:00 18-jan-2005
current log archived
channel t1: starting archive log backupset
channel t1: specifying archive log(s) in backup set
input archive log thread=1 sequence=9 recid=1 stamp=547477014
input archive log thread=1 sequence=10 recid=2 stamp=547562627
input archive log thread=1 sequence=11 recid=3 stamp=547562680
input archive log thread=1 sequence=12 recid=4 stamp=547580133
input archive log thread=1 sequence=13 recid=5 stamp=547623518
input archive log thread=1 sequence=14 recid=6 stamp=547744760
input archive log thread=1 sequence=15 recid=7 stamp=547865707
input archive log thread=1 sequence=16 recid=8 stamp=547915324
channel t1: starting piece 1 at 14:42:08 18-jan-2005
channel t1: finished piece 1 at 14:43:03 18-jan-2005
piece handle=/u01/oracle/archive/archive_ORA920_06gah1hv_6 comment=NONE
channel t1: backup set complete, elapsed time: 00:00:56
channel t1: deleting archive log(s)
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_9.arc recid=1 stamp=547477014
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_10.arc recid=2 stamp=547562627
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_11.arc recid=3 stamp=547562680
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_12.arc recid=4 stamp=547580133
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_13.arc recid=5 stamp=547623518
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_14.arc recid=6 stamp=547744760
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_15.arc recid=7 stamp=547865707
archive log filename=/optware/oracle/admin/ORA920/arch/ORA920_1_16.arc recid=8 stamp=547915324
Finished backup at 14:43:04 18-jan-2005
Starting Control File Autobackup at 14:43:04 18-jan-2005
piece handle=/optware/oracle/9.2.0.1/dbs/c-2554142925-20050118-02 comment=NONE
Finished Control File Autobackup at 14:43:09 18-jan-2005
released channel: t1
The rman clauses from logseq and until logseq
Sometimes you will want to backup only certain archived logs and not all. This is the case, for example, when you ran out of space and you were forced to move the archived logs on disk onto another directory. In this case the clause "archivelog all" would give an error, because rman will not be able to find the files.
run {
allocate channel dev1 type 'sbt_tape';
backup archivelog
from logseq 12 until logseq 15 thread 1
delete input;
}
Keeping an eye on the list above, the command would back up the archived redo logs from ORA920_1_12.arc to ORA920_1_15.arc
Remember that the name depends on the parameter ... in your init.ora In our case the values is ...
RMAN> show
2> 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 ON;
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 '/optware/oracle/9.2.0.1/dbs/snapcf_ORA920.f'; # default
RMAN> list backupset ;
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ --------------------
1 Full 269M DISK 00:01:41 14:31:04 18-jan-2005
BP Key: 1 Status: AVAILABLE Tag: TAG20050118T142923
Piece Name: /u01/oracle/archive/ORA920_01gah0q3_1
List of Datafiles in backup set 1
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- -------------------- ----
1 Full 562946 14:29:24 18-jan-2005 /u01/oradata/ORA920/system01.dbf
2 Full 562946 14:29:24 18-jan-2005 /u02/oradata/ORA920/undo01.dbf
3 Full 562946 14:29:24 18-jan-2005 /u01/oradata/OMF_DATA_ORA920/o1_mf_tools_0ybbwkp7_.dbf
4 Full 562946 14:29:24 18-jan-2005 /u01/oradata/OMF_DATA_ORA920/o1_mf_tbs_data_0ybcd28z_.dbf
5 Full 562946 14:29:24 18-jan-2005 /u01/oradata/ORA920/oem_repository.dbf
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ --------------------
2 Full 4M DISK 00:00:03 14:31:16 18-jan-2005
BP Key: 2 Status: AVAILABLE Tag: TAG20050118T143112
Piece Name: /u01/oracle/archive/ORA920_02gah0th_2
Controlfile Included: Ckp SCN: 563054 Ckp time: 14:31:13 18-jan-2005
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ --------------------
3 Full 4M DISK 00:00:02 14:31:20 18-jan-2005
BP Key: 3 Status: AVAILABLE Tag:
Piece Name: /optware/oracle/9.2.0.1/dbs/c-2554142925-20050118-00
Controlfile Included: Ckp SCN: 563071 Ckp time: 14:31:18 18-jan-2005
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ --------------------
4 Full 4M DISK 00:00:03 14:34:02 18-jan-2005
BP Key: 4 Status: AVAILABLE Tag: TAG20050118T143359
Piece Name: /u01/oracle/archive/controlf_ORA920_04gah12n_4
Controlfile Included: Ckp SCN: 563233 Ckp time: 14:33:59 18-jan-2005
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ --------------------
5 Full 4M DISK 00:00:02 14:34:06 18-jan-2005
BP Key: 5 Status: AVAILABLE Tag:
Piece Name: /optware/oracle/9.2.0.1/dbs/c-2554142925-20050118-01
Controlfile Included: Ckp SCN: 563233 Ckp time: 14:33:59 18-jan-2005
BS Key Size Device Type Elapsed Time Completion Time
------- ---------- ----------- ------------ --------------------
6 203M DISK 00:00:56 14:43:03 18-jan-2005
BP Key: 6 Status: AVAILABLE Tag: TAG20050118T144206
Piece Name: /u01/oracle/archive/archive_ORA920_06gah1hv_6
List of Archived Logs in backup set 6
Thrd Seq Low SCN Low Time Next SCN Next Time
---- ------- ---------- -------------------- ---------- ---------
1 9 118838 12:18:25 13-jan-2005 124198 12:56:51 13-jan-2005
1 10 124198 12:56:51 13-jan-2005 208951 12:43:38 14-jan-2005
1 11 208951 12:43:38 14-jan-2005 209145 12:44:30 14-jan-2005
1 12 209145 12:44:30 14-jan-2005 227914 17:35:21 14-jan-2005
1 13 227914 17:35:21 14-jan-2005 271564 05:38:29 15-jan-2005
1 14 271564 05:38:29 15-jan-2005 392830 15:19:13 16-jan-2005
1 15 392830 15:19:13 16-jan-2005 514138 00:55:00 18-jan-2005
1 16 514138 00:55:00 18-jan-2005 563727 14:42:00 18-jan-2005
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ --------------------
7 Full 4M DISK 00:00:02 14:43:07 18-jan-2005
BP Key: 7 Status: AVAILABLE Tag:
Piece Name: /optware/oracle/9.2.0.1/dbs/c-2554142925-20050118-02
Controlfile Included: Ckp SCN: 563788 Ckp time: 14:43:03 18-jan-2005
RMAN>
Are we sure that our backups do not contain corrupted blocks
There is, of course, little point in taking backups if we don't know whether they are physically usable, i.e. all their blocks are clean. rman offer the command validate
RMAN> validate backupset 6;
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=26 devtype=DISK
channel ORA_DISK_1: starting validation of archive log backupset
channel ORA_DISK_1: restored backup piece 1
piece handle=/u01/oracle/archive/archive_ORA920_06gah1hv_6 tag=TAG20050118T144206 params=NULL
channel ORA_DISK_1: validation complete
RMAN> validate backupset 5;
using channel ORA_DISK_1
channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: restored backup piece 1
piece handle=/optware/oracle/9.2.0.1/dbs/c-2554142925-20050118-01 tag=null params=NULL
channel ORA_DISK_1: validation complete
RMAN> validate backupset 4;
using channel ORA_DISK_1
channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: restored backup piece 1
piece handle=/u01/oracle/archive/controlf_ORA920_04gah12n_4 tag=TAG20050118T143359 params=NULL
channel ORA_DISK_1: validation complete
Clause not backed up since time
There are cases when backups faile and the stand becomes unclear. To avoid any risk the clause not backed up since time can be used. This commands makes rman save only the datafiles (or the archived logs) that haven't be backed up for a certain span of time and skip the rest.
RMAN> run { allocate channel t1 type disk;
2> backup database format '/u01/oracle/archive/%d_%u_%s' not backed up since time 'sysdate -5';
3> release channel t1;}
allocated channel: t1
channel t1: sid=25 devtype=DISK
Starting backup at 15:41:31 21-jan-2005
skipping datafile 1; already backed up on 20:38:51 18-jan-2005
skipping datafile 2; already backed up on 20:38:51 18-jan-2005
skipping datafile 3; already backed up on 20:38:51 18-jan-2005
skipping datafile 4; already backed up on 20:38:51 18-jan-2005
skipping datafile 5; already backed up on 20:38:51 18-jan-2005
Finished backup at 15:41:33 21-jan-2005
released channel: t1
An examples on how to restore a data file can be found on the first article about restoration.
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