Oracle 利用增量备份恢复dataguard gap

其他 2020-01-24 12:35:47 阅读次数: 0

首先说明，这种方法步骤多、比较复杂，更适合量很大重搭dg相当耗时的库，如果是小库，直接重搭更简单。

一、 现象

从库alert日志出现报错，有gap sequence现象。

FAL[client]: Failed to request gap sequence
 GAP - thread 1 sequence 2473-2572
 DBID 2826037382 branch 929228744
FAL[client]: All defined FAL servers have been attempted.

v$archive_gap视图也可看到缺少的归档日志号。

SQL> select * from v$archive_gap;

   THREAD# LOW_SEQUENCE# HIGH_SEQUENCE# 
---------- ------------- -------------- 
         1          2473           2572

二、 修复步骤

1. 停备库日志应用

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

2. 查询备库的scn

用下面两个查询中的最小值在主库进行增量备份。

--防止current_scn以科学计数法显示
col current_scn for 99999999999999999 
SELECT CURRENT_SCN FROM V$DATABASE;

CURRENT_SCN
--------------
3164433

select min(checkpoint_change#) from v$datafile_header
where file# not in (select file# from v$datafile where enabled = 'READ ONLY');

MIN(F.FHSCN)
----------------
3162298
-- 这里应该用3162298

3. 确定主库在此SCN后是否加过数据文件

select FILE#,name from v$datafile where CREATION_CHANGE#>=3162298;

根据主库是否加过数据文件，选择下面不同的操作步骤，注意不要直接在从库add数据文件，会报错的。

4. 主库增量备份并传输到备库上

1）如果主库没加过数据文件

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直接用查到的最小SCN进行增备即可

RMAN> BACKUP INCREMENTAL FROM SCN 3162298 DATABASE FORMAT '/tmp/ForStandby_%U' tag 'FORSTANDBY';

2）如果主库加了数据文件

还需要备份新加的数据文件和主库当前控制文件

RMAN> backup datafile <missing file number>,<missing file number> format '/tmp/ForStandby_%U' tag 'FORSTANDBY';
RMAN> backup incremental from SCN 3162298 database format '/tmp/ForStandby_%U' tag 'FORSTANDBY';
RMAN> backup current controlfile for standby format '/tmp/ForStandbyCTRL.bck';

3）备份文件传到备库

scp /tmp/ForStandby_* standby:/tmp

5. 主库没加过数据文件的备库恢复方法

1）注册恢复文件

rman target /
RMAN> CATALOG START WITH '/tmp/ForStandby';

using target database control file instead of recovery catalog
searching for all files that match the pattern /tmp/ForStandby

List of Files Unknown to the Database
=====================================
File Name: /tmp/ForStandby_2lkglss4_1_1
File Name: /tmp/ForStandby_2mkglst8_1_1

Do you really want to catalog the above files (enter YES or NO)? YES
cataloging files...
cataloging done

List of Cataloged Files
=======================
File Name: /tmp/ForStandby_2lkglss4_1_1
File Name: /tmp/ForStandby_2mkglst8_1_1

2）恢复数据库

RMAN> SHUTDOWN IMMEDIATE ;
RMAN> STARTUP MOUNT;
RMAN> RECOVER DATABASE NOREDO;

starting recover at 03-JUN-09
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=28 devtype=DISK
channel ORA_DISK_1: starting incremental datafile backupset restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
destination for restore of datafile 00001: +DATA/STBY/datafile/system.297.688213333
destination for restore of datafile 00002: +DATA/STBY/datafile/undotbs1.268.688213335
destination for restore of datafile 00003: +DATA/STBY/datafile/sysaux.267.688213333
channel ORA_DISK_1: reading from backup piece /tmp/ForStandby_2lkglss4_1_1
channel ORA_DISK_1: restored backup piece 1
piece handle=/tmp/ForStandby_2lkglss4_1_1 tag=FORSTANDBY
channel ORA_DISK_1: restore complete, elapsed time: 00:00:02
Finished recover at 03-JUN-09

3）备份主库当前控制文件并传到从库

RMAN> BACKUP CURRENT CONTROLFILE FOR STANDBY FORMAT '/tmp/ForStandbyCTRL.bck';

scp /tmp/ForStandbyCTRL.bck standby:/tmp

4）获取从库当前数据文件信息

由于主从库数据文件名、路径可能不同，需要先保存从库数据文件信息，以供还原主库备份的控制文件后参考 。

spool standby_datafile_names.txt
set pagesize 1000;
set lines 200
col name format a60
select file#, name from v$datafile order by file# ;
spool off

5）从库还原备份的控制文件

RMAN> SHUTDOWN IMMEDIATE ;
RMAN> STARTUP NOMOUNT;
RMAN> RESTORE STANDBY CONTROLFILE FROM '/tmp/ForStandbyCTRL.bck';

Starting restore at 03-JUN-09
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=36 devtype=DISK

channel ORA_DISK_1: restoring control file
channel ORA_DISK_1: restore complete, elapsed time: 00:00:07
output filename=+DATA/STBY/controlfile/current.257.688583989
Finished restore at 03-JUN-09

6）mount从库

RMAN> ALTER DATABASE MOUNT;

7）如果数据文件的位置、名称不同，需要在从库Catalog数据文件（相同则跳过此步）

  • 建议在此步骤之前检查主从库化身
RMAN> list incarnation;
  • 对从库数据文件所在的每个磁盘组或目录，执行以下命令
RMAN> CATALOG START WITH '+DATA/STBY/datafile/';

List of Files Unknown to the Database
=====================================
File Name: +DATA/STBY/DATAFILE/SYSTEM.309.685535773
File Name: +DATA/STBY/DATAFILE/SYSAUX.301.685535773
File Name: +DATA/STBY/DATAFILE/UNDOTBS1.302.685535775
File Name: +DATA/STBY/DATAFILE/SYSTEM.297.688213333
File Name: +DATA/STBY/DATAFILE/SYSAUX.267.688213333
File Name: +DATA/STBY/DATAFILE/UNDOTBS1.268.688213335

Do you really want to catalog the above files (enter YES or NO)? YES
cataloging files...
cataloging done

List of Cataloged Files
=======================
File Name: +DATA/STBY/DATAFILE/SYSTEM.297.688213333
File Name: +DATA/STBY/DATAFILE/SYSAUX.267.688213333
File Name: +DATA/STBY/DATAFILE/UNDOTBS1.268.688213335
  • 使用从库正确的数据文件位置和名称更新控制文件
RMAN> SWITCH DATABASE TO COPY;

datafile 1 switched to datafile copy "+DATA/STBY/datafile/system.297.688213333"
datafile 2 switched to datafile copy "+DATA/STBY/datafile/undotbs1.268.688213335"
datafile 3 switched to datafile copy "+DATA/STBY/datafile/sysaux.267.688213333"
  • 如果switch报错"RMAN-06571: datafile .. does not have recoverable copy"。说明尚未catalog所有从库数据文件，或者某些从库数据文件位置、名称与主库相同。
  • 如果是后者，必须只switch位置、名称与主库不同的数据文件。 
RMAN>  switch datafile 5 to copy;
  • 比较当前从库数据文件与还原前（前面的standby_datafile_names.txt）是否有差异，确保已将所有数据文件添加到从库。
  • 再次运行步骤2中的查询，确认增量恢复已前滚数据文件。现在，SCN应该大于初始值。

8）从库配置闪回（可选）

SQL> ALTER DATABASE FLASHBACK OFF; 
SQL> ALTER DATABASE FLASHBACK ON;

9）清除从库所有standby redolog组

SQL> select GROUP# from v$logfile where TYPE='STANDBY' group by GROUP#;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 1;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 2;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 3;

10）从库恢复日志应用

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT;

6. 主库加过数据文件的备库恢复方法

1）恢复新的控制文件并catalog备份文件

RMAN> shutdown;
RMAN> startup nomount;
RMAN> restore standby controlfile from '/tmp/ForStandbyCTRL.bck';
RMAN> alter database mount;

RMAN> CATALOG START WITH '/tmp/ForStandby';

using target database control file instead of recovery catalog
searching for all files that match the pattern /tmp/ForStandby

List of Files Unknown to the Database
=====================================
File Name: /tmp/ForStandby_2lkglss4_1_1
File Name: /tmp/ForStandby_2mkglst8_1_1

Do you really want to catalog the above files (enter YES or NO)? YES
cataloging files...
cataloging done

List of Cataloged Files
=======================
File Name: /tmp/ForStandby_2lkglss4_1_1
File Name: /tmp/ForStandby_2mkglst8_1_1

2）还原主库新建的数据文件

run
{
set newname for datafile X to '+DISKGROUP';
set newname for datafile Y to '+DISKGROUP';
set newname for datafile Z to '+DISKGROUP';
...
restore datafile x,y,z,....;
}

3）重命名新从库控制文件中的数据文件

由于控制文件是从主库恢复的，当前控制文件中即的数据文件路径会跟主库一样。如果从库数据文件路径、名称与主库不同，需要执行此步骤。

RMAN> CATALOG START WITH '+DATA/<db_unqiue_name>/datafile/';

List of Files Unknown to the Database
=====================================
File Name: +data/<db_unqiue_name>/DATAFILE/SYSTEM.309.685535773
File Name: +data/<db_unqiue_name>/DATAFILE/SYSAUX.301.685535773
File Name: +data/<db_unqiue_name>/DATAFILE/UNDOTBS1.302.685535775
File Name: +data/<db_unqiue_name>/DATAFILE/SYSTEM.297.688213333
File Name: +data/<db_unqiue_name>/DATAFILE/SYSAUX.267.688213333
File Name: +data/<db_unqiue_name>/DATAFILE/UNDOTBS1.268.688213335

Do you really want to catalog the above files (enter YES or NO)? YES
cataloging files...
cataloging done

List of Cataloged Files
=======================
File Name: +data/<db_unqiue_name>/DATAFILE/SYSTEM.297.688213333
File Name: +data/<db_unqiue_name>/DATAFILE/SYSAUX.267.688213333
File Name: +data/<db_unqiue_name>/DATAFILE/UNDOTBS1.268.688213335

catalog所有文件后，执行switch the database to copy命令

RMAN> SWITCH DATABASE TO COPY;

datafile 1 switched to datafile copy "+DATA/<db_unqiue_name>/datafile/system.297.688213333"
datafile 2 switched to datafile copy "+DATA/<db_unqiue_name>/datafile/undotbs1.268.688213335"
datafile 3 switched to datafile copy "+DATA/<db_unqiue_name>/datafile/sysaux.267.688213333"

4）恢复备库

RMAN> RECOVER DATABASE NOREDO;

starting recover at 03-JUN-09
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=28 devtype=DISK
channel ORA_DISK_1: starting incremental datafile backupset restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
destination for restore of datafile 00001: +DATA/<db_unqiue_name>/datafile/system.297.688213333
destination for restore of datafile 00002: +DATA/<db_unqiue_name>/datafile/undotbs1.268.688213335
destination for restore of datafile 00003: +DATA/<db_unqiue_name>/datafile/sysaux.267.688213333
channel ORA_DISK_1: reading from backup piece /tmp/ForStandby_2lkglss4_1_1
channel ORA_DISK_1: restored backup piece 1
piece handle=/tmp/ForStandby_2lkglss4_1_1 tag=FORSTANDBY
channel ORA_DISK_1: restore complete, elapsed time: 00:00:02
Finished recover at 03-JUN-09

5）从库配置闪回（可选）

SQL> ALTER DATABASE FLASHBACK OFF; 
SQL> ALTER DATABASE FLASHBACK ON;

6）清除从库所有standby redolog组

SQL> select GROUP# from v$logfile where TYPE='STANDBY' group by GROUP#;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 1;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 2;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 3;

7）从库恢复日志应用

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT;

参考

Steps to perform for Rolling Forward a Physical Standby Database using RMAN Incremental Backup. (Doc ID 836986.1)
Steps to perform for Rolling forward a standby database using RMAN incremental backup when datafile is added to primary (Doc ID 1531031.1)

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