Shulou(Shulou.com)05/31 Report--

Today, I will talk to you about what scn-based recovery is like. Many people may not know much about it. In order to make you understand better, the editor has summarized the following for you. I hope you can get something from this article.

-- back up first: (hot backup)

[oracle@wang ~] $rman target /

Recovery Manager: Release 11.2.0.4.0-Production on Fri Dec 8 19:35:11 2017

Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

Connected to target database: DBDB (DBID=3282897732)

RMAN > backup database

Starting backup at 08-DEC-17

Using target database control file instead of recovery catalog

Allocated channel: ORA_DISK_1

Channel ORA_DISK_1: SID=44 device type=DISK

Channel ORA_DISK_1: starting full datafile backup set

Channel ORA_DISK_1: specifying datafile (s) in backup set

Input datafile file number=00004 name=/u01/app/oracle/oradata/DBdb/users01.dbf

Input datafile file number=00006 name=/u01/app/oracle/fast_recovery_area/DBDB/newback/ts_xxf_01.dbf

Input datafile file number=00001 name=/u01/app/oracle/oradata/DBdb/system01.dbf

Input datafile file number=00003 name=/u01/app/oracle/oradata/DBdb/undotbs01.dbf

Channel ORA_DISK_1: starting piece 1 at 08-DEC-17

Channel ORA_DISK_1: finished piece 1 at 08-DEC-17

Piece handle=/u01/app/oracle/fast_recovery_area/DBDB/newback/DBDB/backupset/2017_12_08/o1_mf_nnndf_TAG20171208T193949_f2nyj5gy_.bkp tag=TAG20171208T193949 comment=NONE

Channel ORA_DISK_1: backup set complete, elapsed time: 00:00:55

Channel ORA_DISK_1: starting full datafile backup set

Channel ORA_DISK_1: specifying datafile (s) in backup set

Input datafile file number=00002 name=/u01/app/oracle/oradata/DBdb/sysaux01.dbf

Input datafile file number=00005 name=/u01/app/oracle/oradata/DBdb/example01.dbf

Channel ORA_DISK_1: starting piece 1 at 08-DEC-17

Channel ORA_DISK_1: finished piece 1 at 08-DEC-17

Piece handle=/u01/app/oracle/fast_recovery_area/DBDB/newback/DBDB/backupset/2017_12_08/o1_mf_nnndf_TAG20171208T193949_f2nykwl2_.bkp tag=TAG20171208T193949 comment=NONE

Channel ORA_DISK_1: backup set complete, elapsed time: 00:00:25

Channel ORA_DISK_1: starting full datafile backup set

Channel ORA_DISK_1: specifying datafile (s) in backup set

Including current control file in backup set

Including current SPFILE in backup set

Channel ORA_DISK_1: starting piece 1 at 08-DEC-17

Channel ORA_DISK_1: finished piece 1 at 08-DEC-17

Piece handle=/u01/app/oracle/fast_recovery_area/DBDB/newback/DBDB/backupset/2017_12_08/o1_mf_ncsnf_TAG20171208T193949_f2nylpqk_.bkp tag=TAG20171208T193949 comment=NONE

Channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

Finished backup at 08-DEC-17

RMAN >

Second, simulation operation:

SQL > select current_scn from v$database

CURRENT_SCN

-

3960846

SQL >

SQL > create table scott.scn_a as select * from dba_objects

Table created.

SQL > select count (*) from scott.scn_a

COUNT (*)

-

87053

SQL > select current_scn from v$database

CURRENT_SCN

-

3960968

SQL >

SQL > create table hr.scn_b as select * from dba_objects

Table created.

SQL > select count (*) from hr.scn_b

COUNT (*)

-

87054

SQL > select current_scn from v$database

CURRENT_SCN

-

3961042

SQL >

SQL > alter system switch logfile

System altered.

SQL >

SQL > select current_scn from v$database

CURRENT_SCN

-

3961063

SQL >

SQL > alter system checkpoint

System altered.

SQL >

SQL > select current_scn from v$database

CURRENT_SCN

-

3961088

-- Delete table scn_a/scn_b:

SQL > drop table scott.scn_a purge

Table dropped.

SQL > drop table hr.scn_b purge

Table dropped.

-- restore:

-- close the library and start to mount status:

SQL > shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL >

SQL > startup mount

ORACLE instance started.

Total System Global Area 835104768 bytes

Fixed Size 2257840 bytes

Variable Size 549456976 bytes

Database Buffers 281018368 bytes

Redo Buffers 2371584 bytes

Database mounted.

SQL >

Enable rman for recovery:

[oracle@wang ~] $rman target /

Recovery Manager: Release 11.2.0.4.0-Production on Fri Dec 8 19:49:38 2017

Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

Connected to target database: DBDB (DBID=3282897732, not open)

RMAN >

RMAN > run {

Set until scn = 3960968

Restore database

Recover database

Alter database open resetlogs;}

Executing command: SET until clause

Starting restore at 08-DEC-17

Using target database control file instead of recovery catalog

Allocated channel: ORA_DISK_1

Channel ORA_DISK_1: SID=20 device type=DISK

Channel ORA_DISK_1: starting datafile backup set restore

Channel ORA_DISK_1: specifying datafile (s) to restore from backup set

Channel ORA_DISK_1: restoring datafile 00001 to / u01/app/oracle/oradata/DBdb/system01.dbf

Channel ORA_DISK_1: restoring datafile 00003 to / u01/app/oracle/oradata/DBdb/undotbs01.dbf

Channel ORA_DISK_1: restoring datafile 00004 to / u01/app/oracle/oradata/DBdb/users01.dbf

Channel ORA_DISK_1: restoring datafile 00006 to / u01/app/oracle/fast_recovery_area/DBDB/newback/ts_xxf_01.dbf

Channel ORA_DISK_1: reading from backup piece / u01/app/oracle/fast_recovery_area/DBDB/newback/DBDB/backupset/2017_12_08/o1_mf_nnndf_TAG20171208T193949_f2nyj5gy_.bkp

Channel ORA_DISK_1: piece handle=/u01/app/oracle/fast_recovery_area/DBDB/newback/DBDB/backupset/2017_12_08/o1_mf_nnndf_TAG20171208T193949_f2nyj5gy_.bkp tag=TAG20171208T193949

Channel ORA_DISK_1: restored backup piece 1

Channel ORA_DISK_1: restore complete, elapsed time: 00:02:15

Channel ORA_DISK_1: starting datafile backup set restore

Channel ORA_DISK_1: specifying datafile (s) to restore from backup set

Channel ORA_DISK_1: restoring datafile 00002 to / u01/app/oracle/oradata/DBdb/sysaux01.dbf

Channel ORA_DISK_1: restoring datafile 00005 to / u01/app/oracle/oradata/DBdb/example01.dbf

Channel ORA_DISK_1: reading from backup piece / u01/app/oracle/fast_recovery_area/DBDB/newback/DBDB/backupset/2017_12_08/o1_mf_nnndf_TAG20171208T193949_f2nykwl2_.bkp

Channel ORA_DISK_1: piece handle=/u01/app/oracle/fast_recovery_area/DBDB/newback/DBDB/backupset/2017_12_08/o1_mf_nnndf_TAG20171208T193949_f2nykwl2_.bkp tag=TAG20171208T193949

Channel ORA_DISK_1: restored backup piece 1

Channel ORA_DISK_1: restore complete, elapsed time: 00:00:25

Finished restore at 08-DEC-17

Starting recover at 08-DEC-17

Using channel ORA_DISK_1

Starting media recovery

Media recovery complete, elapsed time: 00:00:00

Finished recover at 08-DEC-17

Database opened

RMAN >

-- verify:

SQL > select status from v$instance

STATUS

-

OPEN

SQL > select count (*) from scott.scn_a

COUNT (*)

-

87053

SQL >

SQL > select count (*) from hr.scn_b

Select count (*) from hr.scn_b

*

ERROR at line 1:

ORA-00942: table or view does not exist

Because the restore is only to the current_scn queried after the creation of the scn_a table, the table scn_b has not yet been created.

After reading the above, do you have any further understanding of scn-based recovery? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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