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Sharing experience on RMAN backups ...

Sharing experience on RMAN backups. Sydney Oracle Meetup #14. Yury Velikanov Member of Sydney’s Oracle Community. General Guidelines & Concepts. Typical backup flow Nightly/Weekly/Monthly (depends on the DB size) {rARCHs + CTL} + {FULL DB BACKUP + ARCH + CTL}

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Sharing experience on RMAN backups ...

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  1. Sharing experience on RMAN backups ... Sydney Oracle Meetup #14 Yury Velikanov Member of Sydney’s Oracle Community

  2. General Guidelines & Concepts • Typical backup flow • Nightly/Weekly/Monthly (depends on the DB size) {rARCHs + CTL} + {FULL DB BACKUP + ARCH + CTL} • Each 4h/2h/1h/15min (depends on ARHC volumes) {rARCHs + CTL} • To reduce backup’s volumes (size) • Some Nightly/Weekly might be replaced by {INCLEMENTAL}

  3. RMAN: Minimal set of commands Nightly/Weekly/Monthly backup archivelog delete input; backup database; backup current controlfile; backup archivelog delete input; restore controlfile; restore database; recover database; alter database open; backup database plus archivelog delete input; backup database; backup database plus archivelog; Each 4h/2h/1h/15min backup archivelog delete input; backup database; backup current controlfile;

  4. Starting an RMAN session & more set NLS_DATE_FORMAT=YYYY/MM/DD HH24:MI:SS rman target / list backup; show all; -- could be used to restore cfg CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT = 'C:\oracle\backup\df0_%d_%s_%t'; CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO COMPRESSEDBACKUPSET;

  5. RMAN: Advanced set of commands BACKUP ${v_compress} ${v_files_per_set} ${v_max_set_size} ARCHIVELOG ALL NOT BACKED UP ${v_num_arch_bkps} TIMES FORMAT '${v_backup_archlog_format}' ${v_del_input}; BACKUP ${v_compress} ${v_files_per_set} ${v_max_set_size} ARCHIVELOG FROM SEQUENCE ${v_init_sequence_to_start_with} FORMAT '${v_backup_archlog_format}' ${v_del_input};" DELETE NOPROMPT ARCHIVELOG ALL BACKED UP $v_del_arch_copies TIMES TO DISK COMPLETED BEFORE 'TRUNC(SYSDATE-1/(${p_del_arch_oldr_h}*24))'; BACKUP ${v_incremental} ${v_compress} ${v_files_per_set} ${v_max_set_size} DATABASE FORMAT '${v_backup_database_format}'; BACKUP ${v_compress} CURRENT CONTROLFILE FORMAT '${v_backup_controlfile_format}'; BACKUP ${v_compress} SPFILE FORMAT '${v_backup_spfile_format}';"

  6. Implementation Constraints • Are we integrating backups with existing company wise solution? Or backup infrastructure dedicated to Oracle DB backups? • File system or Tape backups • Retention policy management (RMAN or MML) • How many Oracle DBs in the organization? • RMAN Repository • Do we have Oracle RMAN integrated MML solution? • File system or Tape backup • Do we have Enterprise Edition or Standard Edition • ...

  7. RMAN Catalog DB consideration • Use Control file only • IMHO Good choice for most of the cases • Why to manage an additional database? • Default option starting from 9i?10G? • Organizations where retention policy managed by MML • Database count is low • Why use Control file & DB Repository? • Just to have a fun and keep us busy :) • If your organization have many Oracle Databases • If you use OEM databases and it treated as critical resource • If you need to lock some of your backups • If you write a backup script test connection to catalog DB • There might be a strange synchronization issues

  8. Backups Performance Optimization • Empty block skipping (8i) • Stores 1 block for 4 empty block • Applicable to blocks above High Water Mark only • Compressed backups (10g) • Might improve performance 2-4 times if MML is slower then CPU • Doesn’t improve performance if CPU are slower then MML • Advanced Compression in 11g (additional licence) • Parallel backups (8i) • Improves performance significantly if enough IO resources • Might be very powerful in conjunction with compression • Might kill overall system performance as tend to use all resources available

  9. Backups Performance Optimization • Incremental backups (9i) • Improve speed of backups if MML is a a performance bottleneck • Block change tracking (10g) • Increase a speed of incremental backups dramatically • Introduce a slight overhead on regular operations • Read Only tablespaces • CONFIGURE BACKUP OPTIMIZATION ON; • Standby database

  10. Recovery Performance Optimization • If you use tape backups: • Use as small backup sets as reasonable • Depending on MML implementation: one file restore from a backup set (e.g. control file) reads entire backup set • Image copy updatable by incremental backups • Automatic or Manual standby database • Manual in case of Standard Edition

  11. Real World Case 1 (Zipping bck sets) • Constraints • Company wide backup policy/procedures in use • Each server has NFS mounted directory where backups are stored • Each night centralized backup solution backups files in the directory and remove those straight after backup is completed (excluding *.tmp files only) • “Wrong” Solution • RMAN fromat => *.tmp files • Zip scripts triggered after backup, compressing and removing .tmp • log_archive_dest => NFS; backup script => backup and remove ARCHs • “My” Solution :) • RMAN makes backups in *.rman.tmp files • As soon as backup completed "mv *.rman.tmp *.rman“ • Uncatalog / Catalog backup sets

  12. Real World Case 2 (Could we restore?) • Description • Accidentally found that Media Management Layer software metadata stored on the server where backup has been taken • Metadata RMAN Handle map to MML handles • It wouldn’t be possible to restore backups on the other server or if the original server lost complicity • Solution & Take Away • Test recovery on other server than backups were taken from • Keep MML metadata & log files as part of you backups

  13. Real World Case 3 (Extreme Restore) • Description • 3-d party financials application • Application’s module used to manage Oracle structures & parameters • An administrator decided to change PCTUSER parameter for one of the main transactions table • He used (as instructed) the application’s module • Instead of 1-2 seconds the operation took 10 -15 min • The administrator interrupted the operation • Application’s module cleaned up source and target structures • It appears that last valid backup was taken 6 months ago • Solution & Take Away • Oracle Logminer used to restore the table • Use your imagination and be creative

  14. Archivelogs backup management • For strange reasons some DBAs tend to leave ARCHs for some time on a DB server file system (after backup) • In some organizations ARCHs’ backup are separated from data files backups • Data files by RMAN • ARCHs backed up and removed by OS scripts • IMHO: Relative ARCHs should be part of data files backups and stored using the same policy • ARCHs regular backups should be suspended before Data Files backup starts • Some one might say that ARCHs should be stored in more secure place than data file backups. You may chouse to store those twice :)

  15. Practical advice • Don’t change backup set location if possible • Often ZIP backup sets • RMAN Log files should be part of backup • Record Begin/End SCN’s and the log file • Record Timing information • Spool DB and MML version information • May spool file current file structure • spool “show all;” command output in the beginning • Specify data/arch/ctl/sp as part of backup set name

  16. Open Discussion ... • Media Management Layer integration • Retention policy management • Flash recovery area • …

  17. Thank you

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