制造gap
在主库上停止向备库传输日志
SQL> alter system set log_archive_dest_state_2=defer scope=memory; System altered.
在主库进行几次日志切换，并将切换的日志删除，在错误备库的错误日志中可以看到：
Archived Log entry 20 added for thread 1 sequence 123 rlc 913820033 ID 0x55ec8100 dest 2: Tue Jan 21 10:58:49 2020 Fetching gap sequence in thread 1, gap sequence 120-121 Tue Jan 21 11:00:40 2020 FAL[client]: Failed to request gap sequence GAP - thread 1 sequence 120-121 DBID 1441600768 branch 913820033 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. ------------------------------------------------------------ Tue Jan 21 11:05:48 2020 Archived Log entry 21 added for thread 1 sequence 124 rlc 913820033 ID 0x55ec8100 dest 2: RFS[5]: No standby redo logfiles created for thread 1
在备库中检查视图发现：
select * from v$archive_gap; THREAD# LOW_SEQUENCE# HIGH_SEQUENCE# ---------- ------------- -------------- 1 120 121
从主库进行增量SCN的备份
如果能找到日志文件，将其传输过去，注册即可。
SQL> alter database register logfile ‘<File-Specification>’;
如果找不到日志文件，可以按备库当前的SCN号从主库生成一个增量备份恢复到主库 参见文档：https://docs.oracle.com/cd/B19306_01/server.102/b14239/scenarios.htm#CIHIAADC
停止备库的日志应用
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL; Database altered. SQL> select * from v$archive_gap; THREAD# LOW_SEQUENCE# HIGH_SEQUENCE# ---------- ------------- -------------- 1 120 121 SQL> select open_mode from v$database; OPEN_MODE -------------------- READ ONLY
找出备库当前的SCN号：
SQL> SELECT CURRENT_SCN FROM V$DATABASE; CURRENT_SCN ----------- 3085099
查看datafile中有无没有记录log的scn
SQL> SELECT MIN(FIRST_NONLOGGED_SCN) FROM V$DATAFILE WHERE FIRST_NONLOGGED_SCN>0; MIN(FIRST_NONLOGGED_SCN) ------------------------ SQL>
运气不错，没有，好了，现在确定最小的SCN是3085099，从主库以这个SCN开始进行增量备份。
RMAN> BACKUP INCREMENTAL FROM SCN 3085099 DATABASE FORMAT '/tmp/ForStandby_%U' tag 'FORSTANDBY'; Starting backup at 21-JAN-20 using target database control file instead of recovery catalog allocated channel: ORA_DISK_1 channel ORA_DISK_1: SID=46 device type=DISK channel ORA_DISK_1: starting full datafile backup set channel ORA_DISK_1: specifying datafile(s) in backup set input datafile file number=00001 name=/u01/app/oracle/oradata/orcl/system01.dbf input datafile file number=00002 name=/u01/app/oracle/oradata/orcl/sysaux01.dbf input datafile file number=00005 name=/u01/app/oracle/oradata/orcl/example01.dbf input datafile file number=00003 name=/u01/app/oracle/oradata/orcl/undotbs01.dbf input datafile file number=00004 name=/u01/app/oracle/oradata/orcl/users01.dbf channel ORA_DISK_1: starting piece 1 at 21-JAN-20 channel ORA_DISK_1: finished piece 1 at 21-JAN-20 piece handle=/tmp/ForStandby_0iumhqn9_1_1 tag=FORSTANDBY comment=NONE channel ORA_DISK_1: backup set complete, elapsed time: 00:00:25 channel ORA_DISK_1: starting full datafile backup set channel ORA_DISK_1: specifying datafile(s) in backup set including current control file in backup set channel ORA_DISK_1: starting piece 1 at 21-JAN-20 channel ORA_DISK_1: finished piece 1 at 21-JAN-20 piece handle=/tmp/ForStandby_0jumhqo2_1_1 tag=FORSTANDBY comment=NONE channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01 Finished backup at 21-JAN-20 [oracle@rhel65 orcl]$ ls -l /tmp/ForStandby_* -rw-r----- 1 oracle oinstall 14376960 1月 21 14:34 /tmp/ForStandby_0iumhqn9_1_1 -rw-r----- 1 oracle oinstall 10027008 1月 21 14:34 /tmp/ForStandby_0jumhqo2_1_1
把备份的文件传输到备库的机器上
在备库上恢复
将传输的文件在备库上注册。
RMAN> catalog start with '/tmp/ForStandby'; searching for all files that match the pattern /tmp/ForStandby List of Files Unknown to the Database ===================================== File Name: /tmp/ForStandby_0jumhqo2_1_1 File Name: /tmp/ForStandby_0iumhqn9_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_0jumhqo2_1_1 File Name: /tmp/ForStandby_0iumhqn9_1_1
使用report schema检查备库是rman target，并检查文件名。
list backup ..... BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ --------------- 8 Incr 9.55M DISK 00:00:00 21-JAN-20 BP Key: 8 Status: AVAILABLE Compressed: NO Tag: FORSTANDBY Piece Name: /tmp/ForStandby_0jumhqo2_1_1 Control File Included: Ckp SCN: 3104501 Ckp time: 21-JAN-20 BS Key Type LV Size Device Type Elapsed Time Completion Time ------- ---- -- ---------- ----------- ------------ --------------- 9 Incr 13.70M DISK 00:00:00 21-JAN-20 BP Key: 9 Status: AVAILABLE Compressed: NO Tag: FORSTANDBY Piece Name: /tmp/ForStandby_0iumhqn9_1_1 List of Datafiles in backup set 9 File LV Type Ckp SCN Ckp Time Name ---- -- ---- ---------- --------- ---- 1 Incr 3104431 21-JAN-20 /u01/app/oracle/oradata/orcl/system01.dbf 2 Incr 3104431 21-JAN-20 /u01/app/oracle/oradata/orcl/sysaux01.dbf 3 Incr 3104431 21-JAN-20 /u01/app/oracle/oradata/orcl/undotbs01.dbf 4 Incr 3104431 21-JAN-20 /u01/app/oracle/oradata/orcl/users01.dbf 5 Incr 3104431 21-JAN-20 /u01/app/oracle/oradata/orcl/example01.dbf
这里注意检查control file的文件名是’/tmp/ForStandby_0jumhqo2_1_1’，下面恢复的时候要用这个文件名。
SQL> startup force nomount; ORACLE instance started. Total System Global Area 417546240 bytes Fixed Size 2253824 bytes Variable Size 331353088 bytes Database Buffers 79691776 bytes Redo Buffers 4247552 bytes RMAN> restore standby controlfile from '/tmp/ForStandby_0jumhqo2_1_1'; Starting restore at 21-JAN-20 using channel ORA_DISK_1 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/orcl/control01.ctl output file name=/u01/app/oracle/fast_recovery_area/orcl/control02.ctl Finished restore at 21-JAN-20 RMAN> ALTER DATABASE MOUNT; database mounted released channel: ORA_DISK_1 RMAN> RECOVER DATABASE NOREDO; Starting recover at 21-JAN-20 Starting implicit crosscheck backup at 21-JAN-20 allocated channel: ORA_DISK_1 channel ORA_DISK_1: SID=28 device type=DISK Crosschecked 1 objects Finished implicit crosscheck backup at 21-JAN-20 Starting implicit crosscheck copy at 21-JAN-20 using channel ORA_DISK_1 Crosschecked 4 objects Finished implicit crosscheck copy at 21-JAN-20 searching for all files in the recovery area cataloging files... no files cataloged using channel ORA_DISK_1 Finished recover at 21-JAN-20 RMAN>
noredo的意思上后续不要apply archivelog。
注意recover时要小心主库和备库的文件名不一样的情况，要用 SET NEWNAME指定不同的路径再recover database，可以先用report schema查询。
SET NEWNAME FOR DATAFILE 1 TO '/oradata1/system01.dbf'; SET NEWNAME FOR DATAFILE 2 TO '/oradata2/undotbs01.dbf'; SET NEWNAME FOR DATAFILE 3 TO '/oradata3/cwmlite01.dbf'; SET NEWNAME FOR DATAFILE 4 TO '/oradata4/drsys01'; SET NEWNAME FOR DATAFILE 5 TO '/oradata5/example01.dbf'; SET NEWNAME FOR TEMPFILE 1 TO '/disk2/temp01.dbf';
后续检查
SQL> select * from v$archive_gap; no rows selected SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION; Database altered.
