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

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;