因为Oracle archivelog会不断生产，一般会设置定期清理archivelog的排程，类似下面。

但DG环境中因为某些原因导致主库事务没有即使传到standby，而这时如果主库的archivelog也被清理掉了，主备库就产生了日志GAP

export  ORACLE_SID=abc
export  ORACLE_HOME=/u01/product/oracle/
export  PATH=$ORACLE_HOME/bin:$PATH
export NLS_LANG=AMERICAN_AMERICA.AL32UTF8
rman target / <<EOF
run
{
crosscheck archivelog all;
DELETE NOPROMPT ARCHIVELOG until time 'sysdate-7';
}
exit;
EOF

如何能够确保standby日志接收到了，主库archivelog才会被删除呢？

11G 后提供了RMAN的archivelog删除策略

CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON STANDBY;

注：这里是说archivelog在standby目录中接收生产了，并不是被实际应用了。

因为这样说？一种情况standby正常开启，但MPR不开启应用redo，其实standby也能接收主库传递过来的archivelog但并没有被应用，这时主库的archivelog是可以被清理的

默认 CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON NONE;

SHOW ALL 命令能看到

实验

1.关闭standby DB，模拟standby无法接受archivelog

2. 主库rman中配置

CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON STANDBY;

3. 主库切换生成新log，模拟gap

SQL> alter system switch logfile;

SQL> /

4.因为standby未接收到archivelog，对主库备份archivelog同时加了DELETE INPUT清理归档报错RMAM-08120

RMAN> backup format '/data/exp/arch_%T_%s_%U' ARCHIVELOG ALL DELETE INPUT;

Starting backup at 13-MAY-20
current log archived
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 archived log backup set
channel ORA_DISK_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=12585 RECID=25142 STAMP=1040319318
input archived log thread=1 sequence=12586 RECID=25144 STAMP=1040319532
input archived log thread=1 sequence=12587 RECID=25146 STAMP=1040319628
input archived log thread=1 sequence=12588 RECID=25147 STAMP=1040320146
channel ORA_DISK_1: starting piece 1 at 13-MAY-20
channel ORA_DISK_1: finished piece 1 at 13-MAY-20
piece handle=/data/exp/arch_20200513_10_0av041ki_1_1 tag=TAG20200513T174906 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
channel ORA_DISK_1: deleting archived log(s)
archived log file name=/data/epodb/arch/1_12585_893259821.arc RECID=25142 STAMP=1040319318
archived log file name=/data/epodb/arch/1_12586_893259821.arc RECID=25144 STAMP=1040319532
RMAN-08120: WARNING: archived log not deleted, not yet applied by standby
archived log file name=/data/epodb/arch/1_12587_893259821.arc thread=1 sequence=12587
RMAN-08120: WARNING: archived log not deleted, not yet applied by standby
archived log file name=/data/epodb/arch/1_12588_893259821.arc thread=1 sequence=12588
Finished backup at 13-MAY-20

5.因为standby未接收到archivelog，对主库delete archivelog报错RMAM-08120

RMAN> delete archivelog until time 'sysdate' ;

released channel: ORA_DISK_1
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=9 device type=DISK
RMAN-08120: WARNING: archived log not deleted, not yet applied by standby
archived log file name=/data/epodb/arch/1_12587_893259821.arc thread=1 sequence=12587
RMAN-08120: WARNING: archived log not deleted, not yet applied by standby
archived log file name=/data/epodb/arch/1_12588_893259821.arc thread=1 sequence=12588

注：如果带上FORCE参数可以忽略 RMAM-08120直接删除archivelog， delete FORCE archivelog until time 'sysdate' ;

ITPub博客

通过RMAN设置standby接收日志后主库归档日志才可删除

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