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;
restore controlfile;
restore database;
recover database;
alter database open;
backup database;
backup database plus archivelog;
backup database plus archivelog delete input;
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 COMPRESSED BACKUPSET;

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 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