使用DMRAMN执行更新DB_MAGIC恢复
使用RECOVER命令完成数据库恢复工作，可以是基于备份集的恢复工作，也可以是使用本地归档日志的恢复工作。如果还原后，数据已经处于一致性状态了，则可以使用更新DB_MAGIC方式恢复，前提是不需要重做日志。语法如下：
RECOVER DATABASE '' []
[USE DB_MAGIC ] [UNTIL TIME '< 时间串>'] [UNTIL LSN ]; |
RECOVER DATABASE '' FROM BACKUPSET '< 备份集目录>'[DEVICE TYPE DISK|TAPE[PARMS '< 介质参数>']] [IDENTIFIED BY
< 密码> [ENCRYPT WITH < 加密算法>]]
; |
RECOVER DATABASE '' UPDATE DB_MAGIC;
::=
WITH ARCHIVEDIR '< 归档日志目录>'{,'< 归档日志目录>'}
DATABASE：指定还原库目标的dm.ini文件路径。
USE DB_MAGIC：指定本地归档日志对应数据库的DB_MAGIC，若不指定，则默认使用目标恢复数据库的DB_MAGIC。
UNTIL TIME：恢复数据库到指定的时间点。
UNTIL LSN：恢复数据库到指定的LSN。
BACKUPSET：指定用于还原目标数据库的备份集目录。
DEVICE TYPE：指存储备份集的介质类型，支持DISK和TAPE，默认为DISK。DISK表示存储备份集到磁盘，TAPE表示存储到磁带。
PARMS：介质参数，供第三方存储介质（TAPE类型）管理使用。
IDENTIFIED BY：指定备份时使用的加密密码，供还原过程解密使用。
ENCRYPT WITH：指定备份时使用的加密算法，供还原过程解密使用，若未指定，则使用默认算法。
WITH ARCHIVEDIR：本地归档日志搜索目录，若未指定，则仅使用目标库配置本地归档目录，RAC环境还会取REMOTE归档目录。
数据库恢复有三种方式：更新DB_MAGIC恢复、从备份集恢复和从归档恢复，
更新DB_MAGIC恢复
当备份集为脱机备份即备份过程中无日志生成，那么此时还原后的数据库中数据与备份时数据状态一致。在不需要重做归档日志恢复数据的情况下，可以直接更新DB_MAGIC完成数据库恢复。完整的示例如下：
1) 启动RMAN备份数据库，保证服务器处于脱机状态。
RMAN> backup database '/dm_home/dmdba/dmdbms/data/jydm/dm.ini' full backupset '/dm_home/dmdba/dmdbms/data/jydm/bak/db_full_bak_recover_dbmagic'; backup database '/dm_home/dmdba/dmdbms/data/jydm/dm.ini' full backupset '/dm_home/dmdba/dmdbms/data/jydm/bak/db_full_bak_recover_dbmagic'; file dm.key not found, use default license! checking if the database under system path [/dm_home/dmdba/dmdbms/data/jydm] is running...[4]. checking if the database under system path [/dm_home/dmdba/dmdbms/data/jydm] is running...[3]. checking if the database under system path [/dm_home/dmdba/dmdbms/data/jydm] is running...[2]. checking if the database under system path [/dm_home/dmdba/dmdbms/data/jydm] is running...[1]. checking if the database under system path [/dm_home/dmdba/dmdbms/data/jydm] is running...[0]. checking if the database under system path [/dm_home/dmdba/dmdbms/data/jydm] is running, write dmrman info. EP[0] max_lsn: 19945240 BACKUP DATABASE [jydm], execute...... CMD CHECK LSN...... BACKUP DATABASE [jydm], collect dbf...... CMD CHECK ...... DBF BACKUP SUBS...... total 1 packages processed... total 7 packages processed... total 13 packages processed... total 14 packages processed... total 15 packages processed... total 16 packages processed... total 21 packages processed... total 22 packages processed... DBF BACKUP MAIN...... BACKUPSET [/dm_home/dmdba/dmdbms/data/jydm/bak/db_full_bak_recover_dbmagic] END, CODE [0]...... META GENERATING...... total 26 packages processed... total 26 packages processed! CMD END.CODE:[0] backup successfully! time used: 15113.537(ms) RMAN> show backupset '/dm_home/dmdba/dmdbms/data/jydm/bak/db_full_bak_recover_dbmagic'; show backupset '/dm_home/dmdba/dmdbms/data/jydm/bak/db_full_bak_recover_dbmagic'; system path: /dm_home/dmdba/dmdbms/data/jydm db magic: 708657636 permanent magic: 1250320462 rac node: 1 page check: 0 rlog encrypt: 0 external cipher[id/name]: 0/ external hash[id/name]: 0/ length in char: 0 use new hash: 1 page size: 8 KB extent size: 16 case sensitive: 1 log page size: 512 B unicode_flag/charset: 0 data version: 0x7000A sys version: V7.1.6.46-Build(2018.02.08-89107)ENT enable policy: 0 archive flag: 1 blank_pad_mode: 0 crc_check: TRUE backupset sig: BA backupset version: 4009 database name: jydm backup name: DB_FULL_jydm_20200617_192816_000091 backupset description: backupset ID : -1041017958 parent backupset ID: -1 META file size : 86528 compressed level: 0 encrypt type: 0 parallel num: 1 backup range: database mpp_timestamp: 1592393290 ddl_clone: FALSE mpp_flag: FALSE backup level: offline backup type: full without log: FALSE START_LSN: 19945241 START_SEQ: 7798402 END_LSN: 19945240 END_SEQ: 7798401 base START_LSN: -1 base END_LSN: -1 base name: base backupset: backup time: 2020-06-17 19:28:25 min trx start lsn: 19945241 min exec ver: 0x0701060C pkg size: 0x02000000 backupset directory: /dm_home/dmdba/dmdbms/data/jydm/bak/db_full_bak_recover_dbmagic backupset name: db_full_bak_recover_dbmagic backup data file num: 8 backup piece num: 1 $file_seq |$size(KB) |$pos_desc |$content_type 0 |205431 |db_full_bak_recover_dbmagic.bak |DATA $file_seq |$group_id |$group_name |$file_id |$file_path |$mirror_path |$file_len 1 |0 |SYSTEM |0 |/dm_home/dmdba/dmdbms/data/jydm/SYSTEM.DBF| |24117248 2 |1 |ROLL |0 |/dm_home/dmdba/dmdbms/data/jydm/ROLL.DBF| |208666624 3 |4 |MAIN |0 |/dm_home/dmdba/dmdbms/data/jydm/MAIN.DBF| |197132288 4 |5 |BOOKSHOP |0 |/dm_home/dmdba/dmdbms/data/jydm/BOOKSHOP.DBF| |157286400 5 |6 |DMHR |0 |/dm_home/dmdba/dmdbms/data/jydm/DMHR.DBF| |134217728 6 |7 |USERS |0 |/dm_home/dmdba/dmdbms/data/jydm/users01.dbf| |52428800 7 |9 |SYSAUX |0 |/dm_home/dmdba/dmdbms/data/jydm/SYSAWR.DBF| |176160768 8 |10 |FG_PERSON |0 |/dm_home/dmdba/dmdbms/data/jydm/FG_PERSON.DBF| |134217728 $file_seq |$file_path |$file_len |$begin_lsn |$begin_seqno |$begin_rpag_off |$end_lsn |$end_seqno |$create_time |$close_time show backupsets successfully. time used: 3.792(ms)
将源库的数据库备份集传输到目标主机上
[dmdba@shard1 bak]$ scp -r db_full_bak_recover_dbmagic/ dmdba@10.13.13.187:/dm_home/dmdbms/backup/ dmdba@10.13.13.187's password: db_full_bak_recover_dbmagic.bak 100% 201MB 100.3MB/s 00:02 db_full_bak_recover_dbmagic.meta 100% 85KB 84.5KB/s 00:00 [dmdba@shard1 bak]$
2) 准备目标库，可以使用备份库，也可以重新生成库。这里是在别一台服务器上创建新库，重新生成库操作如下：
./dminit path=/opt/dmdbms/data db_name=DAMENG_FOR_RESTORE auto_overwrite=1
但我这里目标库就是源库
3) 校验备份。
RMAN> check backupset '/dm_home/dmdbms/backup/db_full_bak_recover_dbmagic'; check backupset '/dm_home/dmdbms/backup/db_full_bak_recover_dbmagic'; CMD END.CODE:[0] check backupset successfully. time used: 6.093(ms)
4) 还原数据库。
RMAN> restore database '/dm_home/dmdbms/data/dameng_for_recover/dm.ini' from backupset '/dm_home/dmdbms/backup/db_full_bak_recover_dbmagic'; restore database '/dm_home/dmdbms/data/dameng_for_recover/dm.ini' from backupset '/dm_home/dmdbms/backup/db_full_bak_recover_dbmagic'; file dm.key not found, use default license! checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[4]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[3]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[2]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[1]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[0]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running, write dmrman info. RESTORE DATABASE CHECK...... RESTORE DATABASE , dbf collect...... RESTORE DATABASE , dbf refresh ...... RESTORE BACKUPSET [/dm_home/dmdbms/backup/db_full_bak_recover_dbmagic] START...... total 22 packages processed... RESTORE DATABASE , UPDATE ctl file...... RESTORE DATABASE , REBUILD key file...... RESTORE DATABASE , CHECK db info...... RESTORE DATABASE , UPDATE db info...... total 24 packages processed! CMD END.CODE:[0] restore successfully. time used: 49968.844(ms)
5) 恢复数据库。
RMAN> recover database '/dm_home/dmdbms/data/dameng_for_recover/dm.ini' update db_magic; recover database '/dm_home/dmdbms/data/dameng_for_recover/dm.ini' update db_magic; checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[4]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[3]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[2]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[1]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running...[0]. checking if the database under system path [/dm_home/dmdbms/data/dameng_for_recover] is running, write dmrman info. EP[0] max_lsn: 19945240 recover successfully! time used: 7041.721(ms)
6)检查db_magic值，可以确定在没有指定update db_magic选项时其实也是更新了db_maigc值。db_maigc值从708657636变成了-616506144
[root@dmks init.d]# service DmServicedmrc start Starting DmServicedmrc: [ OK ] [dmdba@dmks ~]$ disql SYSDBA/xxzx7817600@localhost:5336 Server[localhost:5336]:mode is normal, state is open login used time: 11.667(ms) disql V7.1.6.46-Build(2018.02.08-89107)ENT Connected to: DM 7.1.6.46 SQL> select permanent_magic; LINEID PERMANENT_MAGIC ---------- --------------- 1 1250320462 used time: 0.305(ms). Execute id is 5. SQL> select db_magic from v$rlog; LINEID DB_MAGIC ---------- ----------- 1 -616506144 used time: 1.948(ms). Execute id is 6.