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LA Oracle Users Group Succeeding with RMAN Tim Gorman Principal SageLogix, Inc.

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Presentation on theme: "LA Oracle Users Group Succeeding with RMAN Tim Gorman Principal SageLogix, Inc."— Presentation transcript:

1 LA Oracle Users Group Succeeding with RMAN Tim Gorman ( Principal SageLogix, Inc.

2 Agenda Is RMAN worth the trouble? Overview of RMAN architecture A little bit o history… RMAN in Oracle8 RMAN in Oracle8i RMAN in Oracle9i Some things that RMAN still doesnt do well Doesnt mean it cant do it, but you just have to figure it out yourself still…

3 Is RMAN Worth It? RMAN has a bad rap Initially well-deserved, but not anymore… Database recovery is too important to rely on ad- libs during recovery situations Just about every DBA has written backup scripts How many have written restore and recovery scripts? And tested all of them? Having a query-able database of all backup, restore, and recovery operations is invaluable for determining recoverability Nothing is better than actually testing a restore/recovery, but RMAN has many almost-as-good features built in

4 Architecture Overview Target database The database which is being/has been backed up The RMAN executable connects to the target database like any other application RMAN allocates channels which are normal Oracle server processes to read datafiles and/or archived redo log files and write them to backup media Type DISK (default) Type SBT_TAPE (requires integration with 3 rd party software) Channels allocated for normal backup/restore/recovery operations or for explicit catalog maintenance purposes Database control files contain the real recovery catalog A database of all backup, restore, and recovery actions as well as structural information about the target database

5 Architectural Overview Recovery Catalog database An optional component Not required, merely a convenience Contains data replicated from the real recovery catalog database in the target databases control files Used to consolidate RMAN recovery information and enable certain advanced features None of the basic backup, restore, or recovery features require a recovery catalog database Auxiliary database Database being created during a DUPLICATE TARGET DATABASE operations Target database is the source database being copied RMAN executable or Backup Manager in OEM Command-line or GUI console for runnig RMAN commands

6 Architectural Overview data files data files online redo logfiles control files Oracle server RMAN Oracle server Backup Manager (OEM) Oracle server Oracle server Target database Recovery Catalog Backup media MMV

7 RMAN in Oracle8 Introduced in Oracle8 (circa 1997) Uses server processes to perform backups to disk (default) or integrated backup media manager (configurable) No need for FULL block images to redo to prevent fractured block corruption As with ALTER TABLESPACE BEGIN/END BACKUP Backs up database (datafiles, redo logfiles, controlfiles) and archived redo logfiles BACKUP or COPY commands Performs block-level backups Has incremental backup capability Performs corruption checking during backup Server processes perform same block checks as SELECT statement Reporting capabilities on all backup, restore, recovery operations from repository

8 RMAN in Oracle8i Enhanced in Oracle8i DUPLICATE TARGET DATABASE command added Create DEV, QA/TEST, or prod scratch databases from PROD Cumulative incremental backups added Reduces restore time at a cost of larger backups than default differential incremental backups Crosscheck RMAN catalog with MML catalog or disk files to expire records Keeps recovery catalog up-to-date and valid Fewer commands requiring a separate recovery catalog database Complete list in Recovery Manager Users Guide, page 3-45 in Oracle8i and page 3-13 in Oracle9i

9 RMAN in Oracle8i Trial restores and backups Reads data from backup media, scans them and verifies checksums for completeness, but does not restore to database RESTORE CONTROLFILE VALIDATE; RESTORE DATABASE VALIDATE; RESTORE TABLESPACE … VALIDATE; RESTORE DATAFILE … VALIDATE; RESTORE ARCHIVELOG … VALIDATE; VALIDATE BACKUPSET … Similar BACKUP … VALIDATE commands also exist

10 Simple database backup $ rman nocatalog Recovery Manager: Release – Production Copyright © 1995, 2002, Oracle Corporation. All rights res RMAN> connect target sys/manager Connected to target database: GRDEV1 (DBID=2234098234) Using target database controlfile instead of recovery cata RMAN> run { 2> allocate channel t1 type SBT_TAPE; 3> allocate channel t2 type SBT_TAPE; 4> allocate channel t3 type SBT_TAPE; 5> backup incremental level=0 maxsetsize 4G database; 6> release channel t1; 7> release channel t2; 8> release channel t2; 9> }

11 Simple archivelog backup $ rman nocatalog Recovery Manager: Release – Production Copyright © 1995, 2002, Oracle Corporation. All rights re RMAN> connect target sys/manager Connected to target database: GRDEV1 (DBID=2234098234) Using target database controlfile instead of recovery cat RMAN> run { 2> sql alter system switch logfile; 3> allocate channel t1 type SBT_TAPE; 4> backup filesperset 10 archivelog delete input; 5> release channel t1; 6> }

12 RMAN everyday tasks Other typical RMAN responsibilities Maintain recovery catalog entries Cross-check against MMV catalog Delete expired/obsolete entries from catalog and media Reporting Report on redundancy of backups on backup media Report on whether anything needs to be backed up Report on NOLOGGING activity

13 RMAN in Oracle9i Persistent configuration Configuration settings stored in control file Allows simpler everyday command syntax Defaults for all BACKUP, COPY, RESTORE operations CONFIGURE DEFAULT DEVICE TYPE xxx Where xxx is usually either DISK or SBT (tape) CONFIGURE DEVICE TYPE xxx [ PARALLELISM n ] Determines how many channels to allocate by default

14 RMAN in Oracle9i Persistent configuration (contd) CONFIGURE CONTROLFILE AUTOBACKUP [ON|OFF] Automatically backs up controlfile and SPFILE After BACKUP, COPY, and other RMAN commands After structural changes to database detected CONFIGURE RETENTION POLICY TO REDUNDANCY nn Where nn is the number of complete backups TO RECOVERY WINDOW OF nn DAYS Where backups and archived redo logs must be retained to allow recoveries to any point-in-time within the nn day recovery window


16 RMAN in Oracle9i Oracle9i Server parameter files (SPFILEs) Can be automatically backed up with controlfiles Can be explicitly backed up with: BACKUP SPFILE Must be restored with: RESTORE SPFILE TO [ xxx | PFILE yyy ]

17 RMAN in Oracle9i Improvements in treatment of archived redo logfiles BACKUP … PLUS ARCHIVELOGS … Automatic log switching prior to any backup of archivelogs Convenient… No error message if any backup of archivelogs does not find any files Good riddance to a real annoyance… Automatic failover between logfile members if a sequence is missing Both a good and a bad thing…

18 RMAN in Oracle9i Control files Use CONFIGURE AUTOBACKUP to automatically backup controlfiles Highly recommended! Controlfiles can be backed up explicitly using: BACKUP CURRENT CONTROLFILE BACKUP … DATABASE | TABLESPACE xxx | DATAFILE xxx INCLUDE CURRENT CONTROLFILE If all controlfiles are lost or damaged, can be restored: RESTORE CONTROLFILE

19 RMAN in Oracle9i Simplified catalog maintenance commands DELETE OBSOLETE Deletes catalog entries and backupset files according to configured retention policy DELETE EXPIRED CROSSCHECK command detects expired backupset files if missing from backup media Deletion deletes the entries from recovery catalog and target database controlfiles

20 RMAN in Oracle9i Block-level media recovery Instead of restoring and recovering entire datafiles Blocks being recovered must have already been identified as corrupt by RMAN V$BACKUP_CORRUPTION V$COPY_CORRUPTION V$DATABASE_BLOCK_CORRUPTION Allows the database to stay up and available during restore and recovery Attempts to access blocks being recovered results in error message that block is marked corrupt

21 RMAN in Oracle9i Block-level media recovery (contd) Typical error indicating corrupt database block: ORA-01578: ORACLE data block corrupted (file #3, block #177) ORA-01110: data file 3: '/u00/oradata/FDDP/undotbs01.dbf' Can be restored and recovered with: BLOCKRECOVER DATAFILE 3 BLOCK 177; Restrictions: Can only be performed using a FULL backup No incremental backups permitted

22 RMAN in Oracle9i Managing disk space during restores RESTORE DATABASE restores datafiles RECOVER DATABASE restores archived redo log files and performs database recovery In prior versions, this was done in 2 simple steps Easy to run out of space during recovery RECOVER … DELETE ARCHIVELOG … MAXSIZE nnn Restores nnn Mbytes or Gbytes of archived redo log files at a time Uses them for recovery, then deletes them Until recovery completed

23 RMAN in Oracle9i DUPLICATE TARGET enhancements SKIP TABLESPACE allows duplication of a subset of the target database Remaining (unskipped) tablespaces can be recovered to a previous point-in-time, if desired Useful for recovering tablespaces or individual tables

24 Things RMAN doesnt do The REPORT command leaves much to be desired There is a REPORT NEEDS BACKUP, REPORT OBSOLETE, and REPORT UNRECOVERABLE But there is no REPORT ISRECOVERABLE yet And isnt this the most important thing to know? Must write a custom report against repository to accomplish this, still… Archived redo log files retention policies are not supported RMAN just wants to DELETE INPUT after successful backup Maybe not a bad thing…

25 Additional documentation MetaLink Note #131865.1 RMAN Library Index An incredible online resource for RMAN! Oracle Press Oracle9i RMAN Backup and Recovery Robert Freeman, Matthew Hart – Oct 2002 Oracle Backup and Recovery 101 Stephen Haisley, Kenny Smith – Mar 2002 Oracle8i Backup & Recovery Rama Velpuri – Nov 2000 OReilly and Associates Oracle RMAN Pocket Reference Darl Kuhn, Scott Schulze – Nov 2001

26 Q&A Slides downloadable from

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