18c中用一条命令将RMAN增量备份前滚到物理备库

Oracle Database - Enterprise Edition - 版本 18.1.0.0.0 和更高版本

在此文档中，以如下虚拟环境为例来描述这个过程：
Standby Name: SBY180
Primary Name: PRM180
Directory Name: /u01/app/oracle and all sub-directories

通常，当使用主库的增量备份对一个物理备库执行前滚操作时，需要多个步骤

确定备库上的起始SCN，从而在主库上执行增量备份
使用FROM SCN语句在主库上执行增量备份
将备份片从主库移动到备库
在备库上对备份片执行catalog
在备库上使用recover database noredo执行恢复
从主库再次刷新备库控制文件
从12.1开始，我们可以使用"RECOVER DATABASE FROM SERVICE"命令，它会自动处理一些步骤，比如在主库上执行增量备份，通过网络转移备份片到备库，以及在备库上执行恢复。然而，我们仍然必须手动刷新备库控制文件并手动还原新增加的数据文件。这些步骤需要手动执行，并且易于带来错误，尤其是当备库文件的物理位置与主库不同的时候。

从18.1开始，我们可以使用一条命令来将主库上的改变刷新到备库:

RMAN> RECOVER STANDBY DATABASE FROM SERVICE primary_connect_identifier;

这条命令会内部的追踪备库文件的位置，从主库刷新备库控制文件，用备库文件名更新新的备库控制文件，在主库执行增量备份，通过网络转移备份片到备库并且在备库执行恢复。

1. 要刷新备库，确保备库上managed recovery已经停止:

SQL> recover managed standby database cancel;

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1. 如果备库是拥有超过一个实例的RAC环境，那么确保仅仅要执行recover standby命令的实例是mount状态，而其它所有实例都被关闭，这样可避免遇到 RMAN-05157。
2. 在物理备库的tnsnames.ora文件中增加一个对应主库的条目，以确保主库和备库之间的Oracle网络连接已经建立，在下面的例子中，PRM180是到主库的连接标识符.
3. 使用RMAN以target模式连接到备库，运行 "RECOVER STANDBY DATABASE FROM SERVICE"命令，下面是一个运行这条命令的例子:

$ export ORACLE_SID=SBY180
$ rman target / 

RMAN> RECOVER STANDBY DATABASE FROM SERVICE PRM180;

RMAN-03090: Starting recover at 03-AUG-18
RMAN-06009: using target database control file instead of recovery catalog
RMAN-06196: Oracle instance started

Total System Global Area 671086904 bytes

Fixed Size 8661304 bytes
Variable Size 188743680 bytes
Database Buffers 465567744 bytes
Redo Buffers 8114176 bytes

RMAN-08161: contents of Memory Script:
{
restore standby controlfile from service 'PRM180';
alter database mount standby database;
}
RMAN-08162: executing Memory Script

RMAN-03090: Starting restore at 03-AUG-18
RMAN-08030: allocated channel: ORA_DISK_1
RMAN-08500: channel ORA_DISK_1: SID=141 device type=DISK

RMAN-08016: channel ORA_DISK_1: starting datafile backup set restore
RMAN-08169: channel ORA_DISK_1: using network backup set from service PRM180
RMAN-08021: channel ORA_DISK_1: restoring control file
RMAN-08180: channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
RMAN-08505: output file name=/u01/app/oracle/oradata/SBY180/control01.ctl
RMAN-03091: Finished restore at 03-AUG-18

RMAN-08031: released channel: ORA_DISK_1
RMAN-06986: Statement processed
RMAN-06958: Executing: alter system set standby_file_management=manual

RMAN-08161: contents of Memory Script:
{
recover database from service 'PRM180';
}
RMAN-08162: executing Memory Script

RMAN-03090: Starting recover at 03-AUG-18
RMAN-08030: allocated channel: ORA_DISK_1
RMAN-08500: channel ORA_DISK_1: SID=149 device type=DISK
RMAN-06179: datafile 4 not processed because file is read-only
RMAN-08039: channel ORA_DISK_1: starting incremental datafile backup set restore
RMAN-08169: channel ORA_DISK_1: using network backup set from service PRM180
RMAN-08509: destination for restore of datafile 00001: /u01/app/oracle/oradata/SBY180/system01.dbf
RMAN-08180: channel ORA_DISK_1: restore complete, elapsed time: 00:00:03
RMAN-08039: channel ORA_DISK_1: starting incremental datafile backup set restore
RMAN-08169: channel ORA_DISK_1: using network backup set from service PRM180
RMAN-08509: destination for restore of datafile 00002: /u01/app/oracle/oradata/SBY180/sysaux01.dbf
RMAN-08180: channel ORA_DISK_1: restore complete, elapsed time: 00:00:07
RMAN-08039: channel ORA_DISK_1: starting incremental datafile backup set restore
RMAN-08169: channel ORA_DISK_1: using network backup set from service PRM180
RMAN-08509: destination for restore of datafile 00003: /u01/app/oracle/oradata/SBY180/undotbs01.dbf
RMAN-08180: channel ORA_DISK_1: restore complete, elapsed time: 00:00:03

RMAN-08054: starting media recovery

RMAN-08181: media recovery complete, elapsed time: 00:00:00
RMAN-03091: Finished recover at 03-AUG-18
RMAN-06958: Executing: alter system set standby_file_management=auto
RMAN-03091: Finished recover at 03-AUG-18

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