Recovering from Noncritical Losses Copyright © 2006, Oracle. All rights reserved. Objectives After completing this lesson, you should be able to: • Recover temporary tablespaces • Recover a redo log group member • Recover from a lost index • Re-create the password file 4-2 Copyright © 2006, Oracle. All rights reserved. Causes of File Loss File loss can be caused by: • User error • Application error • Media failure 4-3 Copyright © 2006, Oracle. All rights reserved. Critical Versus Noncritical A noncritical file loss is one where the database can continue to function. You fix the problem by taking one of these actions: • Create a new file. • Rebuild the file. • Recover the lost or damaged file. 4-4 Copyright © 2006, Oracle. All rights reserved. Losing a TEMPFILE SQL statements that require TEMP space to execute fail if one of the tempfiles is missing. SQL> select * from big_table order by 1,2,3,4,5,6,7,8,9,10,11,12,13; select * from big_table order by 1,2,3,4,5,6,7,8,9,10,11,12,13 * ERROR at line 1: ORA-01565: error in identifying file '/u01/app/oracle/oradata/orcl/temp01.dbf' ORA-27037: unable to obtain file status Linux Error: 2: No such file or directory 4-5 Copyright © 2006, Oracle. All rights reserved. Recovering from a TEMPFILE Loss SYSTEM USERS Redo log Redo log file 1A file 1B SYSAUX INDEX Redo log Redo log file 2A file 2B UNDO TEMP Control files Parameter file Password file 4-6 Copyright © 2006, Oracle. All rights reserved. Log Group Status: Review A redo log group has a status of one of the following values at any given time: • CURRENT: The LGWR process is currently writing redo data to it. • ACTIVE: It is no longer being written to, but it is still required for instance recovery. • INACTIVE: It is no longer being written to, and it is no longer required for instance recovery. 4-7 Copyright © 2006, Oracle. All rights reserved. Losing a Redo Log Group Member The alert log and the archiver process (ARCn) trace file record an error when a redo member file is missing. Errors in file /u01/app/oracle/admin/orcl/bdump/orcl_arc1_25739.trc: ORA-00313: open failed for members of log group 2 of thread 1 ORA-00312: online log 2 thread 1: '/u01/app/oracle/oradata/orcl/redo02b.log' ORA-27037: unable to obtain file status Linux Error: 2: No such file or directory 4-8 Copyright © 2006, Oracle. All rights reserved. Re-creating Redo Log Files SYSTEM USERS Redo log Redo log file 1A file 1B SYSAUX INDEX Redo log Redo log file 2A file 2B UNDO TEMP Control files Parameter file Password file SQL> > SQL> SQL> > > 4-9 ALTER DATABASE DROP LOGFILE MEMBER '/u01/app/oracle/oradata/orcl/redo02b.log'; !rm /u01/app/oracle/oradata/orcl/redo02b.log ALTER DATABASE ADD LOGFILE MEMBER '/u01/app/oracle/oradata/orcl/redo02b.log' TO GROUP 2; Copyright © 2006, Oracle. All rights reserved. Re-creating Redo Log Files 4-12 Copyright © 2006, Oracle. All rights reserved. Re-creating Indexes Use options to reduce the time it takes to create the index: • PARALLEL • NOLOGGING SQL> CREATE INDEX rname_idx 2 ON hr.regions (region_name) 3 PARALLEL 4; 4-13 Copyright © 2006, Oracle. All rights reserved. Authentication Methods for Database Administrators Remote database administration Do you have a secure connection? Local database administration Yes No 4-15 Do you want to use OS authentication? Yes No Copyright © 2006, Oracle. All rights reserved. Use OS authentication. Use a password file. Re-creating a Password Authentication File 1. Log in to the database by using OS authentication. 2. Set the REMOTE_LOGIN_PASSWORDFILE parameter to NONE and restart the database. 3. Re-create the password file by using orapwd. $ orapwd file=$ORACLE_HOME/dbs/orapwORCL password=admin entries=5 4. Set REMOTE_LOGIN_PASSWORDFILE to EXCLUSIVE. 5. Add users to the password file and assign appropriate privileges to each user. 6. Restart the instance. 4-16 Copyright © 2006, Oracle. All rights reserved. Summary In this lesson, you should have learned how to: • Recover temporary tablespaces • Recover a redo log group member • Recover from a lost index • Re-create the password file 4-18 Copyright © 2006, Oracle. All rights reserved. Practice Overview: Recovering from Lost TEMPFILE and Redo Log File This practice covers the following topics: • Starting the database with a missing tempfile • Creating a new temporary tablespace • Altering the default temporary tablespace for a database • Recovering from a lost online redo log member 4-19 Copyright © 2006, Oracle. All rights reserved.