Recovery Manager Concepts

Transcription

1 Recovery Manager Concepts Joseph S Testa Data Management Consulting (64) Ohio Oracle Users Group Apr 2003

2 Introduction Who is using RMAN for backup/recovery? Have you tested your recovery scenarios? How about the full disaster where you have to manually extract the control file?

3 Definitions System Change Number(SCN) Control File Data Block Datafile Tablespace

4 Definitions (cont) Online Redo Log Archive Redo Log Rollback Segment Undo Segment (NO) Archivelogmode

5 Definitions (cont) Backup Restore Recovery Target database Repository database

6 Recovery Manager (RMAN) Overview OS utility that can backup/restore/recover Oracle Database files. Its found under $ORACLE_HOME/bin Be aware there are other RMAN commands (rman - reverse compile man pages from formatted form to a number of source formats)

7 Overview (cont) Target Database: the one you'll be backing up. Repository: not mandatory but its extremely smart to use one. Maintains metadata about your backups. There is also 3 rd party hooks into other management systems.

8 Repository Create repository owner/user Grant RECOVERY_CATALOG_OWNER and create session to that user. Connect to the repository and run 'create catalog'. Connect to target(needs SYSDBA role) and register the database.

9 Starting/Exiting RMAN [ TARGET [=] connectstringspec { CATALOG [=] connectstringspec NOCATALOG } LOG [=] ['] filename ['] RMAN> EXIT

10 Configuration Show all Configure Disk Devices/Channels Allocate channel/configure allocate channel disk device type disk format '/u0/rman_backups/%d/%d_%s_%t_%p' maxpiecesize = 999m;

11 Configuration Format Specifiers %c :Specifies the copy number of the backup piece within a set of duplexed backup pieces. If you did not duplex a backup, then this variable is for backup sets and 0 for proxy copies. If one of these commands is enabled, then the variable shows the copy number. The maximum value for %c is 256.

12 Configuration Format Specifiers %d : Specifies the name of the database. %D : Specifies the current day of the month from the Gregorian calendar in format DD.

13 Configuration Format Specifiers %F : Combines the DBID, day, month, year, and sequence into a unique and repeatable generated name. %M : Specifies the month in the Gregorian calendar in format MM.

14 Configuration Format Specifiers %n : Specifies the name of the database, padded on the right with x characters to a total length of eight characters. For example, if the sand is the database name, then the padded name is sandxxxx.

15 Configuration Format Specifiers %p : Specifies the piece number within the backup set. This value starts at for each backup set and is incremented by as each backup piece is created.

16 Configuration Format Specifiers %s : Specifies the backup set number. This number is a counter in the control file that is incremented for each backup set. The counter value starts at and is unique for the lifetime of the control file. If you restore a backup control file, then duplicate values can result.

17 Configuration Format Specifiers %t : Specifies the backup set time stamp, which is a 4-byte value derived as the number of seconds elapsed since a fixed reference time. The combination of %s and %t can be used to form a unique name for the backup set.

18 Configuration Format Specifiers %T : Specifies the year, month, and day in the Gregorian calendar in this format: YYYYMMDD. %u : Specifies an 8-character name constituted by compressed representations of the backup set number and the time the backup set was created.

19 Configuration Format Specifiers %U : Specifies a convenient shorthand for %u_%p_%c that guarantees uniqueness in generated backup filenames. If you do not specify a format, then RMAN uses %U by default. %Y : Specifies the year in this format: YYYY

20 Backing up Database Files Full Database Backup(not part of incremental backup strategy) { } run allocate channel disk device type disk format '/u0/rman_backups/%d/%d_%s_%t_%p' maxpiecesize = 999m; backup database;

21 Backing up Database Files Incremental Database Backup(0) { } run allocate channel disk device type disk format '/u0/rman_backups/%d/%d_%s_%t_%p' maxpiecesize = 999m; backup incremental level = 0 database plus archivelog;

22 Backing up Database Files Incremental Database Backup() { } run allocate channel disk device type disk format '/u0/rman_backups/%d/%d_%s_%t_%p' maxpiecesize = 999m; backup cumulative level = database plus archivelog;

23 Backing up Database Files Tablespace Backup { } run allocate channel disk device type disk format '/u0/rman_backups/%d/%d_%s_%t_%p' maxpiecesize = 999m; backup tablespace tools;

24 Reporting List backup; List backup summary; List backup of database completed after before between 'SYSDATE - $DAYS_DIFFERENCE';

25 Managing the repository Crosscheck backup; Purpose: TO ensure that the backups are on disk/tape and are accessible via the medium. If they are not available they are marked as expired and will not be used for restore purposes.

26 Managing the repository Delete backup; Purpose:!!EXTREMELY DESTRUCTIVE, This command will wipe out all metadata about backups, can you still restore if you had to????

27 Managing the repository Delete backupset <nnn>; Purpose: To delete metadata about backups based on a backupset number, a definite better alternative to DELETE BACKUP;

28 Managing the repository Delete expired backup; Purpose: To delete backup metadata from the repository after using the crosscheck command.

29 Restoring Datafiles System TS: db must not be open Non System TS: offline ts, restore tablespace <tsname>; Control files Restore controlfile; ALWAYS requires open resetlogs

30 Restoring (cont) Archived Redo Logs Restore archivelog all; Not really needed as RMAN will restore the logs as needed(assuming you backed them up) :)

31 Restoring (cont) Server Parameter file Start database with either pfile or without. Restore spfile(9i feature).

32 Recovering(these all assume the restore is done) Complete Database Recover database; Tablespace Recover tablespace <tsname>; Datafile Recover datafile <fname or abs fn>;

33 Recovering Incomplete Time-based RECOVER DATABASE UNTIL TIME "TO_DATE('04/0/2003','MM/DD/YYYY')"; Cancel-based(really sequence based) SET UNTIL SEQUENCE 234 THREAD ; RECOVER DATABASE;

34 Recovering (cont) Temporary Tablespaces(with tempfiles NOT datafiles). RMAN does NOT backup tempfiles that are part of temporary tablespaces, hence there is nothing to restore. Dump the controlfile to trace and backup the trace file.

35 Recovering (cont) Incomplete (cont) Change-based(really SCN based) RECOVER DATABASE UNTIL SCN = ###; As in user managed recovery, when doing incomplete, it requires open resetlogs.

36 Verify/Validate Backups Its as simple as doing: Restore database validate; It will take as long to do this command as it would to do a true restore. You can use this to ensure your backups are good and gives you an estimate of how long it will take to do disaster recovery. Try that with User Managed Backups :)

37 What does "open resetlogs" do? Discards any redo information that was not applied during recovery, ensuring that it will never be applied. Reinitializes the control file metadata about online redo logs and redo threads.

38 What does "open resetlogs" do? (cont) Erases the contents of the online redo logs. Creates the online redo log files if they do not currently exist. Resets the log sequence number to. DOES NOT RESET SCN COUNTER

39

40 RMAN ADVANCED FEATURES Controlfile backup extraction Block Level Recovery Readonly Tablespace Issues Recovering to a previous incarnation Standby Database Creation Cloning Database Creation

41 Controlfile backup extraction Previous to 9i, you had to call support. Now: you'll have to use dbms_backup_restore package manually to extract the controlfile from the backup piece.

42 Controlfile backup extraction(cont) In 8i(or 9i with total loss of repository), it would look like this: devtype:=dbms_backup_restore.deviceal locate(null); dbms_backup_restore.restoresetdatafil e; dbms_backup_restore.restorecontrolfil eto('/tmp/sand_control0.ctl');

43 Block Level Recovery RMAN can restore just blocks that have gone corrupted instead of entire datafiles(9i feature). Using blockrecover command like this: blockrecover datafile block 22;

44 Readonly Tablespace Issues By default RMAN will NOT restore read only tablespace datafiles even if they do not exist on the disk. You must do a restore database check readonly; command to get those restored.

45 Recovering to a previous incarnation Incarnation what is that? When does it happen? How does it happen? Why do you care? Reset database;

46 Standby Database Creation Use RMAN to make a standby controlfile. Build standby directories (either local server or remote). Setup standby init.ora file Build standby password file

47 Standby Database Creation (cont) Put standby in nomount mode. Make sure standby is accessible via tnsnames. RMAN: connect to target and auxiliary(and catalog if need be). RMAN: duplicate target database for standby;

48 Cloning Database Creation Same concepts as standby except command is Duplicate target database to auxiliary name;

49 RMAN FRAMEWORK This is a set of unix shell scripts that I developed and licensed under GPL. They are available free for the asking and Data Management Consulting can assist with implementation.

50 Contact Info Office: Fax: Cell: Nextel Direct: 36*6907* Website:

51 Demo Level 0 Backup is already done(rman_backup.sh sand 0) Restore: Tablespace(rman_restore.sh sand t users) Database (rman_restore.sh sand f) If time, we can do total DR recovery(rman_restore.sh sand fc)