Recover Oracle Database upon losing all Control Files

Transcription

1 Recover Oracle Database upon losing all Control Files R.Wang Oct 19, 07 (Firstly, published at OraclePoint.com ) Preface: This is experimental case study about recovering oracle database upon losing all control files. This experimental is conducted on Windows XP Professional with Oracle database in archivelog mode Steps of Experiment 1. Backup control file SQL> alter database backup controlfile to 'C:\oracle\product\10.2.0\oradata\orcl\control_back.ctl'; 2. Add new tablespace SQL> create tablespace rec_test_1 datafile 'C:\oracle\product\10.2.0\oradata\orcl\rec_test_1.dbf' size 3M; Tablespace created. SQL> create table t_test_1 (n number) tablespace rec_test_1; Table created. SQL> insert into t_test_1 values(1); 1 row created. SQL> commit; Commit complete. 3. Do complete database shutdown and then database open SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ORACLE instance started.

2 Total System Global Area bytes Fixed Size bytes Variable Size bytes Database Buffers bytes Redo Buffers bytes Database mounted. Database opened. 4. Do incomplete shutdown (needs recovery) SQL> shutdown abort; ORACLE instance shut down. 5. Delete all control files (simulate media error) Delete all of the control files of database I m working on. 6. Find time point upon which you want to recover In alert log file (alert_orcl.log in my case), we noticed that following entries. Fri Oct 19 12:33: alter database backup controlfile to 'C:\oracle\product\10.2.0\oradata\orcl\control_back.ctl' Fri Oct 19 12:33: Completed: alter database backup controlfile to 'C:\oracle\product\10.2.0\oradata\orcl\control_back.ctl' Fri Oct 19 12:34: create tablespace rec_test_1 datafile 'C:\oracle\product\10.2.0\oradata\orcl\rec_test_1.dbf' size 3M Fri Oct 19 12:34: Completed: create tablespace rec_test_1 datafile 'C:\oracle\product\10.2.0\oradata\orcl\rec_test_1.dbf' size 3M Fri Oct 19 12:35: In this case, we d like to recover the tablespace newly created. So, we pick the time point Fri Oct 19 12:35: as showed in color red. 7. Check the latest written redo log file SQL> startup mount ORACLE instance started. Total System Global Area bytes Fixed Size bytes Variable Size bytes Database Buffers bytes Redo Buffers bytes Database mounted. SQL> select group#, thread#, sequence#, bytes, members,archived, status from v$log; GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARCHIV STATUS NO CURRENT

3 YES UNUSED YES UNUSED SQL> select group#, status, type, substr(member, 1,48) from v$logfile; GROUP# STATUS TYPE SUBSTR(MEMBER,1,48) ONLINE C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REDO03.LOG 2 ONLINE C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REDO02.LOG 1 ONLINE C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REDO01.LOG So, the logfile C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REDO01.LOG is the one we need to use to recover database. 8. Recover database upon the time point found above SQL> recover database using backup controlfile until time ' :35:20'; ORA-00279: change generated at 10/19/ :31:52 needed for thread 1 C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\ORCL\ARCHIVELOG\2007_10_19\O1 _MF_1_20_%U_.ARC ORA-00280: change for thread 1 is in sequence #20 C:\oracle\product\10.2.0\oradata\orcl\redo01.log ORA-00283: recovery session canceled due to errors ORA-01244: unnamed datafile(s) added to control file by media recovery ORA-01110: data file 7: 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REC_TEST_1.DBF' ORA-01112: media recovery not started Due to backup control file was created before adding new tablespace, the control file doesn t contain information of newly created tablespace rec_test_1. Comparably, archived redo logfile contains the name of this tablespace. That s the reason that error ORA and ORA were raised. 9. Alter name of datafile which is not shown in backup control At this circumstance, the only thing we need to do is to change the name of data file 7 to datafile of newly created tablespace t_test_1. This action will have control file recognize the datafile of tablespace t_test_1. SQL> alter database create datafile 7 as 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REC_TEST_1.DBF';

4 10. Retry the recovery without identifying time point as of step 8 SQL> recover database using backup controlfile; ORA-00279: change generated at 10/19/ :34:16 needed for thread 1 C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\ORCL\ARCHIVELOG\2007_ 10_19\O1_MF_1_20_%U_.ARC ORA-00280: change for thread 1 is in sequence #20 C:\oracle\product\10.2.0\oradata\orcl\redo01.log Log applied. Media recovery complete. After that, Log applied and Media recovery complete show that media recovery is done successfully. 11. Open database with resetlogs option SQL> alter database open resetlogs; SQL> select * from t_test_1; N Query on table t_test_1 (in tablespace rec_test_1) is successful. That means database is recovered without losing tablespace rec_test_1. Note: 1. If the redo log file is not identified properly, the following error will occur. SQL> recover database using backup controlfile until time ' :35:20'; ORA-00279: change generated at 10/19/ :31:52 needed for thread 1 C:\ORACLE\PRODUCT\10.2.0\FLASH_RECOVERY_AREA\ORCL\ARCHIVELOG\2007_10 _19\O1_MF_1_20_%U_.ARC ORA-00280: change for thread 1 is in sequence #20 C:\oracle\product\10.2.0\oradata\orcl\redo03.log ---- in this case, should be redo01.log ORA-00328: archived log ends at change , need later change ORA-00334: archived log: 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REDO03.LOG' ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below ORA-01194: file 1 needs more recovery to be consistent ORA-01110: data file 1: 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\SYSTEM01.DBF'

5 2. It s impossible to recover database at this circumstance if the database is in noarchivelog mode. Ahout the Author: R. Wang currently works as Oracle DBA in Canada. He is responsible for database performance tuning and high availability. With over 10 years experience in architecting and building oracle systems, Rui is an evangelist for oracle technology and products. Rui is OCP and received master degree in computer science from Simon Fraser University in Canada. Visit Rui s blog at