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這篇文章給大家分享的是有關 Oracle 數(shù)據(jù)庫恢復教程之 resetlogs 操作的示例分析的內(nèi)容。丸趣 TV 小編覺得挺實用的，因此分享給大家做個參考，一起跟隨丸趣 TV 小編過來看看吧。
實驗環(huán)境：RHEL 5.4 + Oracle 11.2.0.3
如果是一名合格的 Oracle DBA，對 resetlogs 這種關鍵字都應該是極其敏感的，當確認需要這種操作時一定要三思而后行，如果自己不是特別確認，哪怕多花些時間申請去讓高級 DBA 人員協(xié)助你一起確認，也不要擅自去嘗試執(zhí)行，避免誤操作造成既定損失后追悔莫及。
1. 哪些場景可以 resetlogs
首先要明確 resetlogs 操作非常危險的，也只有在進行不完全恢復開庫時會使用到。
SQL alter database open resetlogs;
- open the database and reset the online logs官方的描述如下：
Incomplete recovery, also called database point-in-time recovery, results in a noncurrent version of the database. In this case, you do not apply all of the redo generated after the restored backup. Typically, you perform point-in-time database recovery to undo a user error when Flashback Database is not possible.
To perform incomplete recovery, you must restore all data files from backups created before the time to which you want to recover and then open the database with the RESETLOGS option when recovery completes. Resetting the logs creates a new stream of log sequence numbers starting with log sequence 1.
官方的描述其實很清晰，但是實際很多初級 DBA 小伙伴們在實際工作中遇到這樣的場景時卻總是有些困惑，甚至誤操作引發(fā)災難。
我這里以一個實驗來具體說明常見場景：
需求：A 機數(shù)據(jù)庫 PROD1，現(xiàn)需在 B 機不同目錄下用 A 機的備份集恢復出來；
A 機：
-- A 機當前 current redolog 的 sequence 是 57:
SQL select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ ---------
1 1 55 52428800 512 1 YES INACTIVE 2051572 19-MAY-19 2060361 19-MAY-19
2 1 56 52428800 512 1 YES INACTIVE 2060361 19-MAY-19 2060436 19-MAY-19
3 1 57 52428800 512 1 NO CURRENT 2060436 19-MAY-19 2.8147E+14
-- A 機做了一次數(shù)據(jù)庫備份：RMAN backup database include current controlfile plus archivelog delete all input;
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=23 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=189 device type=DISK
allocated channel: ORA_DISK_3
channel ORA_DISK_3: SID=21 device type=DISK
channel ORA_DISK_1: starting compressed archived log backup set
channel ORA_DISK_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=57 RECID=3 STAMP=1008670991
channel ORA_DISK_1: starting piece 1 at 19-MAY-19
channel ORA_DISK_1: finished piece 1 at 19-MAY-19
piece handle=/home/oracle/backup/0cu1u68l_1_1.bak tag=TAG20190519T102315 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=/u01/app/oracle/product/11.2.0/dbhome_1/dbs/arch2_57_860888149.dbf RECID=3 STAMP=1008670991
Finished backup at 19-MAY-19
Starting backup at 19-MAY-19
using channel ORA_DISK_1
using channel ORA_DISK_2
using channel ORA_DISK_3
channel ORA_DISK_1: starting compressed full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00002 name=/u01/app/oracle/oradata/PROD1/sysaux01.dbf
channel ORA_DISK_1: starting piece 1 at 19-MAY-19
channel ORA_DISK_2: starting compressed full datafile backup set
channel ORA_DISK_2: specifying datafile(s) in backup set
input datafile file number=00001 name=/u01/app/oracle/oradata/PROD1/system01.dbf
input datafile file number=00004 name=/u01/app/oracle/oradata/PROD1/users01.dbf
channel ORA_DISK_2: starting piece 1 at 19-MAY-19
channel ORA_DISK_3: starting compressed full datafile backup set
channel ORA_DISK_3: specifying datafile(s) in backup set
input datafile file number=00005 name=/u01/app/oracle/oradata/PROD1/example01.dbf
input datafile file number=00003 name=/u01/app/oracle/oradata/PROD1/undotbs01.dbf
channel ORA_DISK_3: starting piece 1 at 19-MAY-19
channel ORA_DISK_3: finished piece 1 at 19-MAY-19
piece handle=/home/oracle/backup/0fu1u68p_1_1.bak tag=TAG20190519T102319 comment=NONE
channel ORA_DISK_3: backup set complete, elapsed time: 00:00:26
channel ORA_DISK_3: starting compressed full datafile backup set
channel ORA_DISK_3: specifying datafile(s) in backup set
including current control file in backup set
channel ORA_DISK_3: starting piece 1 at 19-MAY-19
channel ORA_DISK_3: finished piece 1 at 19-MAY-19
piece handle=/home/oracle/backup/0gu1u69j_1_1.bak tag=TAG20190519T102319 comment=NONE
channel ORA_DISK_3: backup set complete, elapsed time: 00:00:01
channel ORA_DISK_1: finished piece 1 at 19-MAY-19
piece handle=/home/oracle/backup/0du1u68p_1_1.bak tag=TAG20190519T102319 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:01:03
channel ORA_DISK_2: finished piece 1 at 19-MAY-19
piece handle=/home/oracle/backup/0eu1u68p_1_1.bak tag=TAG20190519T102319 comment=NONE
channel ORA_DISK_2: backup set complete, elapsed time: 00:01:23
Finished backup at 19-MAY-19
Starting backup at 19-MAY-19
current log archived
using channel ORA_DISK_1
using channel ORA_DISK_2
using channel ORA_DISK_3
channel ORA_DISK_1: starting compressed archived log backup set
channel ORA_DISK_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=58 RECID=4 STAMP=1008671084
channel ORA_DISK_1: starting piece 1 at 19-MAY-19
channel ORA_DISK_1: finished piece 1 at 19-MAY-19
piece handle=/home/oracle/backup/0hu1u6bg_1_1.bak tag=TAG20190519T102446 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=/u01/app/oracle/product/11.2.0/dbhome_1/dbs/arch2_58_860888149.dbf RECID=4 STAMP=1008671084
Finished backup at 19-MAY-19
Starting Control File and SPFILE Autobackup at 19-MAY-19
piece handle=/home/oracle/backup/control/c-2082231315-20190519-01 comment=NONE
Finished Control File and SPFILE Autobackup at 19-MAY-19
RMAN
-- 可以看到備份數(shù)據(jù)庫的日志前后都自動歸檔了當前的 redolog（57 和 58），所以備份完成后，當前日志 sequence 變?yōu)?59.
SQL select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- --------- ------------ ---------
1 1 58 52428800 512 1 YES INACTIVE 2060691 19-MAY-19 2060767 19-MAY-19
2 1 59 52428800 512 1 NO CURRENT 2060767 19-MAY-19 2.8147E+14
3 1 57 52428800 512 1 YES INACTIVE 2060436 19-MAY-19 2060691 19-MAY-19此時把備份集傳輸?shù)?B 機，比如 /u03/backup 目錄下，期望恢復到 /u03/oradata/PROD1 目錄下。如果最終只是根據(jù)這個備份集去恢復，那最多恢復完 sequence 58 就結束了，找不到 sequence 59（因為 59 還是當前 current 的 redolog）。Oracle 認為這就是最基本的不完全恢復，需要 resetlogs 操作。
-- 指定恢復到 /u03/oradata/
RMAN run {
2 set newname for database to /u03/oradata/PROD1/%U
3 restore database;
4 }
-- 切換到上步恢復出來的 copy 復本：RMAN switch database to copy;
datafile 1 switched to datafile copy /u03/oradata/PROD1/data_D-PROD1_TS-SYSTEM_FNO-1
datafile 2 switched to datafile copy /u03/oradata/PROD1/data_D-PROD1_TS-SYSAUX_FNO-2
datafile 3 switched to datafile copy /u03/oradata/PROD1/data_D-PROD1_TS-UNDOTBS1_FNO-3
datafile 4 switched to datafile copy /u03/oradata/PROD1/data_D-PROD1_TS-USERS_FNO-4
datafile 5 switched to datafile copy /u03/oradata/PROD1/data_D-PROD1_TS-EXAMPLE_FNO-5
-- 嘗試恢復數(shù)據(jù)庫：RMAN recover database;
Starting recover at 19-MAY-19
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=102 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=9 device type=DISK
allocated channel: ORA_DISK_3
channel ORA_DISK_3: SID=112 device type=DISK
starting media recovery
channel ORA_DISK_1: starting archived log restore to default destination
channel ORA_DISK_1: restoring archived log
archived log thread=1 sequence=58
channel ORA_DISK_1: reading from backup piece /home/oracle/backup/0hu1u6bg_1_1.bak
channel ORA_DISK_1: errors found reading piece handle=/home/oracle/backup/0hu1u6bg_1_1.bak
channel ORA_DISK_1: failover to piece handle=/u03/backup/0hu1u6bg_1_1.bak tag=TAG20190519T102446
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
archived log file name=/u01/app/oracle/product/11.2.0/db_1/dbs/arch2_58_860888149.dbf thread=1 sequence=58
unable to find archived log
archived log thread=1 sequence=59
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of recover command at 05/19/2019 11:04:21
RMAN-06054: media recovery requesting unknown archived log for thread 1 with sequence 59 and starting SCN of 2060767
RMAN可以看到最后有報錯信息，就是告訴你找不到 sequence 59 的日志，這是必然的，因為 59 還是 A 機 current 的 redo 日志。
2.resetlogs 前必須確認路徑正確
2.1 先查看控制文件和數(shù)據(jù)文件頭記錄的 scn 是否一致
SQL select checkpoint_change# from v$datafile;
CHECKPOINT_CHANGE#
------------------
2060767
2060767
2060767
2060767
2060767
SQL select checkpoint_change# from v$datafile_header;
CHECKPOINT_CHANGE#
------------------
2060767
2060767
2060767
2060767
20607672.2 此時如果嘗試直接 OPEN 會報錯
SQL alter database open;
alter database open
ERROR at line 1:
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open提示我們開庫必須使用 RESETLOGS 或者 NORESETLOGS 選項。
2.3 重點來了，現(xiàn)在可以 open resetlogs 嗎？
當然不行！記得一定要確認好路徑！！
-- 查詢發(fā)現(xiàn)臨時文件以及 redo 日志的路徑都不是我們所期望的：SQL select name from v$datafile; -------------------------------------------------------------------------------- /u03/oradata/PROD1/data_D-PROD1_TS-SYSTEM_FNO-1 /u03/oradata/PROD1/data_D-PROD1_TS-SYSAUX_FNO-2 /u03/oradata/PROD1/data_D-PROD1_TS-UNDOTBS1_FNO-3 /u03/oradata/PROD1/data_D-PROD1_TS-USERS_FNO-4 /u03/oradata/PROD1/data_D-PROD1_TS-EXAMPLE_FNO-5 SQL select name from v$tempfile; -------------------------------------------------------------------------------- /u01/app/oracle/oradata/PROD1/temp01.dbf SQL select member from v$logfile; MEMBER -------------------------------------------------------------------------------- /u01/app/oracle/oradata/PROD1/redo03.log /u01/app/oracle/oradata/PROD1/redo02.log /u01/app/oracle/oradata/PROD1/redo01.log --rename 重命名為我們期望的目錄：SQL alter database rename file /u01/app/oracle/oradata/PROD1/temp01.dbf to /u03/oradata/PROD1/temp01.dbf Database altered. SQL alter database rename file /u01/app/oracle/oradata/PROD1/redo01.log to /u03/oradata/PROD1/redo01.log Database altered. SQL alter database rename file /u01/app/oracle/oradata/PROD1/redo02.log to /u03/oradata/PROD1/redo02.log Database altered. SQL alter database rename file /u01/app/oracle/oradata/PROD1/redo03.log to /u03/oradata/PROD1/redo03.log Database altered. -- 再次檢查確認：SQL select name from v$tempfile; -------------------------------------------------------------------------------- /u03/oradata/PROD1/temp01.dbf SQL select member from v$logfile; MEMBER -------------------------------------------------------------------------------- /u03/oradata/PROD1/redo03.log /u03/oradata/PROD1/redo02.log /u03/oradata/PROD1/redo01.log -- 最終嘗試 open 開庫：SQL alter database open; alter database open ERROR at line 1: ORA-01589: must use RESETLOGS or NORESETLOGS option for database open
Database altered.
感謝各位的閱讀！關于“Oracle 數(shù)據(jù)庫恢復教程之 resetlogs 操作的示例分析”這篇文章就分享到這里了，希望以上內(nèi)容可以對大家有一定的幫助，讓大家可以學到更多知識，如果覺得文章不錯，可以把它分享出去讓更多的人看到吧！
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