使用RMAN增量备份处理Dataguard因归档丢失造成的gap
场景：
备库执行日志应用出现如下报错：
Thu Mar 29 11:21:45 2018
FAL[client]: Failed to request gap sequence
GAP - thread 1 sequence 184-185
DBID 1484954774 branch 960494131
FAL[client]: All defined FAL servers have been attempted.
------------------------------------------------------------
Check that the CONTROL_FILE_RECORD_KEEP_TIME initialization
parameter is defined to a value that's sufficiently large
enough to maintain adequate log switch information to resolve
archivelog gaps.
查询缺失的归档日志：
SQL> select * from v$archive_gap;
THREAD# LOW_SEQUENCE# HIGH_SEQUENCE#
---------- ------------- --------------
1 183 185
去主库查看归档，发现归档已丢失
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /u01/archivelog
Oldest online log sequence 186
Next log sequence to archive 188
Current log sequence 188
[oracle@prim archivelog]$ pwd
/u01/archivelog
[oracle@prim archivelog]$ ls -ltr
total 1964
-rw-r----- 1 oracle oinstall 74752 Mar 29 11:17 1_186_960494131.dbf
-rw-r----- 1 oracle oinstall 1930240 Mar 29 11:17 1_187_960494131.dbf
下面开始使用RMAN进行基于SCN增量备份恢复的方式进行恢复，参考文档 ID 836986.1
1.取消备库日志应用
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE cancel;
2.在备库上确定需要开始增量备份的SCN
SQL> SELECT CURRENT_SCN FROM V$DATABASE;
CURRENT_SCN
-----------
3505254
SQL> select min(checkpoint_change#) from v$datafile_header
where file# not in (select file# from v$datafile where enabled = 'READ ONLY');
MIN(CHECKPOINT_CHANGE#)
-----------------------
(如果结果为空，重启备库到mount状态)
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 1002127360 bytes
Fixed Size 2259440 bytes
Variable Size 285214224 bytes
Database Buffers 708837376 bytes
Redo Buffers 5816320 bytes
Database mounted.
SQL> select min(checkpoint_change#) from v$datafile_header
where file# not in (select file# from v$datafile where enabled = 'READ ONLY');
MIN(CHECKPOINT_CHANGE#)
-----------------------
3505255
选择以上结果中最小SCN作为增量备份的起点（此处是350524）。
3.在主库上进行基于SCN的增量备份
RMAN> BACKUP INCREMENTAL FROM SCN 3505254 DATABASE FORMAT '/tmp/ForStandby_%U' tag 'FORSTANDBY';
4.拷贝刚才的备份到备库
scp /tmp/ForStandby_* 192.168.211.162:/tmp
5.将拷贝过来的备份注册到备库的控制文件中
[oracle@stand ~]$ rman target /
Recovery Manager: Release 11.2.0.4.0 - Production on Thu Mar 29 11:37:52 2018
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
connected to target database: ORCL (DBID=1484954774, not open)
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_08sv0bdj_1_1
File Name: /tmp/ForStandby_07sv0bcg_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_08sv0bdj_1_1
File Name: /tmp/ForStandby_07sv0bcg_1_1
6.使用增量备份恢复备库
RMAN> RECOVER DATABASE NOREDO;
Starting recover at 29-MAR-18
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=16 device type=DISK
channel ORA_DISK_1: starting incremental datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
destination for restore of datafile 00001: /u01/app/oracle/oradata/rzorcl/system01.dbf
destination for restore of datafile 00002: /u01/app/oracle/oradata/rzorcl/sysaux01.dbf
destination for restore of datafile 00003: /u01/app/oracle/oradata/rzorcl/undotbs01.dbf
destination for restore of datafile 00004: /u01/app/oracle/oradata/rzorcl/users01.dbf
destination for restore of datafile 00005: /u01/app/oracle/oradata/rzorcl/example01.dbf
destination for restore of datafile 00006: /u01/app/oracle/oradata/rzorcl/odc_tps01.dbf
destination for restore of datafile 00007: /u01/app/oracle/oradata/rzorcl/test01.dbf
destination for restore of datafile 00008: /u01/app/oracle/oradata/rzorcl/big01.dbf
destination for restore of datafile 00009: /u01/app/oracle/oradata/rzorcl/big02.dbf
channel ORA_DISK_1: reading from backup piece /tmp/ForStandby_07sv0bcg_1_1
channel ORA_DISK_1: piece handle=/tmp/ForStandby_07sv0bcg_1_1 tag=FORSTANDBY
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
Finished recover at 29-MAR-18
7.在主库为备库重新备份控制文件，并scp到备库
RMAN> BACKUP CURRENT CONTROLFILE FOR STANDBY FORMAT '/tmp/ForStandbyCTRL.bck';
Starting backup at 29-MAR-18
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=9 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including standby control file in backup set
channel ORA_DISK_1: starting piece 1 at 29-MAR-18
channel ORA_DISK_1: finished piece 1 at 29-MAR-18
piece handle=/tmp/ForStandbyCTRL.bck tag=TAG20180329T114413 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 29-MAR-18
[oracle@prim tmp]$ scp ForStandbyCTRL.bck 192.168.211.162:/tmp
oracle@192.168.211.162's password:
ForStandbyCTRL.bck 100% 9856KB 9.6MB/s 00:00
8.备库还原控制文件：
RMAN> shutdown immediate;
database dismounted
Oracle instance shut down
RMAN> startup nomount;
connected to target database (not started)
Oracle instance started
Total System Global Area 1002127360 bytes
Fixed Size 2259440 bytes
Variable Size 285214224 bytes
Database Buffers 708837376 bytes
Redo Buffers 5816320 bytes
RMAN> RESTORE STANDBY CONTROLFILE FROM '/tmp/ForStandbyCTRL.bck';
Starting restore at 29-MAR-18
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=10 device type=DISK
channel ORA_DISK_1: restoring control file
channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
output file name=/u01/app/oracle/oradata/rzorcl/control01.ctl
output file name=/u01/app/oracle/oradata/rzorcl/control02.ctl
Finished restore at 29-MAR-18
9.重启备库到mount
RMAN> SHUTDOWN;
RMAN> STARTUP MOUNT;
10.如果数据库是用OMF方式管理数据文件的，则需要在备库的控制文件中重新注册下数据文件，示例如下：
（如果数据文件存放在文件系统，没有使用OMF，则跳过此步骤）
RMAN> CATALOG START WITH '+DATA/rzorcl/datafile/';
List of Files Unknown to the Database
=====================================
File Name: +data/rzorcl/DATAFILE/SYSTEM.309.685535773
File Name: +data/rzorcl/DATAFILE/SYSAUX.301.685535773
File Name: +data/rzorcl/DATAFILE/UNDOTBS1.302.685535775
File Name: +data/rzorcl/DATAFILE/SYSTEM.297.688213333
File Name: +data/rzorcl/DATAFILE/SYSAUX.267.688213333
File Name: +data/rzorcl/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/rzorcl/DATAFILE/SYSTEM.297.688213333
File Name: +data/rzorcl/DATAFILE/SYSAUX.267.688213333
File Name: +data/rzorcl/DATAFILE/UNDOTBS1.268.688213335
确保主库在这个SCN之后没有添加新的数据文件，如果有则需要单独进行备份和还原，参考文档文档 ID 836986.1
SQL> select file#,name from v$datafile where creation_change# > 3505254;
no rows selected
RMAN> SWITCH DATABASE TO COPY;
datafile 1 switched to datafile copy "+DATA/rzorcl/datafile/system.297.688213333"
datafile 2 switched to datafile copy "+DATA/rzorcl/datafile/undotbs1.268.688213335"
datafile 3 switched to datafile copy "+DATA/rzorcl/datafile/sysaux.267.688213333"
11. 若备库开启了闪回，需要重新开启闪回
SQL> ALTER DATABASE FLASHBACK OFF;
SQL> ALTER DATABASE FLASHBACK ON;
12. 备库clear standby log group
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 4;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 5;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 6;
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 7;
13. 备库开启日志应用,至此整个过程结束
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;