Oracle DataGuard利用rman增量恢复处理gap

原创章芋文 2020-05-07

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alert 日志报错信息：

Media Recovery Waiting for thread 1 sequence 7057
Fetching gap sequence in thread 1, gap sequence 7057-7080
FAL[client]: Error fetching gap sequence, no FAL server specified
Mon Mar 24 11:39:40 CST 2017
FAL[client]: Failed to request gap sequence 
 GAP - thread 1 sequence 7057-7080
 DBID 768411208 branch 784810891
FAL[client]: All defined FAL servers have been attempted.
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出现原因：

DataGuard主备之间可能由于网络等原因，造成备库和主库之间的归档日志不一致，这样就产生了gap。
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处理：

1）主库暂定备库的日志传输
SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2 = 'DEFER';

2）备库取消日志应用
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

3）在备库查询最小的SCN号
SQL> SELECT MIN(FHSCN) FROM X$KCVFH;

   MIN(FHSCN)
 ----------------
20606344

4）例如备库查询的最小SCN号，在主库进行SCN的增量备份
rman target / 
run{
allocate channel c1 device type disk;
allocate channel c2 device type disk;
allocate channel c3 device type disk;
allocate channel c4 device type disk;
sql 'alter system archive log current';
backup as compressed backupset INCREMENTAL FROM SCN 20606344 DATABASE FORMAT '/backup/backup/incr_%d_%T_%U';
crosscheck archivelog all;
BACKUP CURRENT CONTROLFILE FOR STANDBY FORMAT  '/u01/backup/cntrl_%s_%p_%s.ctl';
release channel c1;
release channel c2;
release channel c3;
release channel c4;
}

5）复制增量备份文件到备库

6）备库注册备份文件
RMAN> CATALOG START WITH '/tmp/Standby_Inc';

7）利用RMAN recover恢复备库，此时会默认使用之前注册的备份文件
RMAN> RECOVER DATABASE NOREDO;

8）更新standby 控制文件

RMAN> SHUTDOWN;
RMAN> STARTUP NOMOUNT;
RMAN> RESTORE STANDBY CONTROLFILE FROM '/tmp/Standby_CTRL.bck';
RMAN> SHUTDOWN;
RMAN> STARTUP MOUNT;

9）查询恢复后的数据文件
SQL>SELECT FILE#, NAME FROM V$DATAFILE WHERE CREATION_CHANGE# > 20606344;


10）重启日志传输
SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2 = 'enable' scope=both;

11）重启日志应用
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;
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