Oracle數據庫恢復之resetlogs

時間 2019-12-08

原文原文鏈接

實驗環境：RHEL 5.4 + Oracle 11.2.0.3
若是是一名合格的Oracle DBA，對resetlogs這種關鍵字都應該是極其敏感的，當確認須要這種操做時必定要三思然後行，若是本身不是特別確認，哪怕多花些時間申請去讓高級DBA人員協助你一塊兒確認，也不要擅自去嘗試執行，避免誤操做形成既定損失後追悔莫及。數據庫

1.哪些場景能夠resetlogs

首先要明確resetlogs操做很是危險的，也只有在進行不徹底恢復開庫時會使用到。oracle

SQL> alter database open resetlogs;
-> open the database and reset the online logs

官方的描述以下：app

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.測試

官方的描述其實很清晰，可是實際不少初級DBA小夥伴們在實際工做中遇到這樣的場景時卻老是有些困惑，甚至誤操做引起災難。
我這裏以一個實驗來具體說明常見場景：
需求：A機數據庫PROD1，現需在B機不一樣目錄下用A機的備份集恢復出來；this

A機：rest

--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機作了一次數據庫備份：
RMAN> backup database include current controlfile plus archivelog delete all input;


Starting backup at 19-MAY-19
current log archived
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/arch1_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/arch1_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> 

--能夠看到備份數據庫的日誌先後都自動歸檔了當前的redolog（57和58），因此備份完成後，當前日誌sequence變爲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

此時把備份集傳輸到B機，好比/u03/backup目錄下，指望恢復到/u03/oradata/PROD1目錄下。若是最終只是根據這個備份集去恢復，那最多恢復完sequence 58就結束了，找不到sequence 59（由於59仍是當前current的redolog）。Oracle認爲這就是最基本的不徹底恢復，須要resetlogs操做。日誌

--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複本：
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"

--嘗試恢復數據庫：
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/arch1_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>

能夠看到最後有報錯信息，就是告訴你找不到sequence 59的日誌，這是必然的，由於59仍是A機current的redo日誌。code

2.resetlogs前必須確認路徑正確

2.1 先查看控制文件和數據文件頭記錄的scn是否一致orm

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
           2060767

2.2 此時若是嘗試直接OPEN會報錯ci

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

提示咱們開庫必須使用RESETLOGS或者NORESETLOGS選項。

2.3 重點來了，如今能夠open resetlogs嗎？
固然不行！記得必定要確認好路徑！！

--查詢發現臨時文件以及redo日誌的路徑都不是咱們所指望的：
SQL> select name from v$datafile;

NAME
--------------------------------------------------------------------------------
/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;

NAME
--------------------------------------------------------------------------------
/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重命名爲咱們指望的目錄：
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;

NAME
--------------------------------------------------------------------------------
/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


SQL> alter database open resetlogs;

Database altered.

總結：不少初級人員有多是對set newname for database這個有誤解，覺得這裏的database包括了臨時文件，redo日誌文件，誤覺得本身已經把新庫全部路徑都指向到了指望位置。但實際並非這樣，這也說明了不確認的操做必定要在測試環境測試驗證後才能夠在生產環境操做。你們能夠想象一下，若是是理解有誤沒確認日誌路徑直接執行了resetlogs，那麼若是B機正好有別的庫用到同名的這些路徑，亦或是整個恢復操做就是直接在A機的本機其餘目錄臨時基於某個時間點恢復出一套庫，那將會是一場大的生產事故。