Flash Recovery Area Friend or Foe ?

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Flash Recovery Area Friend or Foe ?
Babette Turner-Underwood The Pythian Group 2007
April
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Oracle Flash Technology

• Flashback Query
• Flashback Versions Query
• Flashback Transaction Query
• Flashback Table
• Flashback Drop
• Flash Backup Recovery
• Flashback Database

X
X
X
X
X
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Oracle Flash Technology

• Based on OMF (Oracle Managed Files)
• File system or ASM
• Automated space management
• Used by
• Database Creation
• Archivelogs
• Flashback Database
• RMAN backups

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Flash Recovery Area (FRA)
Permanent Contents
Redo log
Control file
Transient Files
Archived Redo logs
Flashback logs
RMAN Backups
RMAN Backups
Archived Redo logs
RMAN Backups
RMAN Backups
RMAN Backups
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Configure Flash Recovery Area

• DB_RECOVERY_FILE_DEST
• Specifies the physical disk location (or ASM Disk
  group) for Flash Recovery Area files
• DB_RECOVERY_FILE_DEST_SIZE
• Total size of all files that can be stored in
  Flash Recovery Area
• Excludes files placed there manually

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Configure Flash Recovery Area

• DB_RECOVERY_FILE_DEST_SIZE
• Flashback logs
• Full image copy of database
• Incremental backups
• Archived redo logs
• Online redo logs
• Controlfiles
• Controlfile Autobackups

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Configure Flash Recovery Area

• ALTER SYSTEM SET
• db_file_recovery_dest_size '2G
• SCOPEBOTH SID''
• ALTER SYSTEM SET
• db_file_recovery_dest
• 'C\oracle\product\10.2.0\flash_recovery_area'

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Automatic File Creation in FRA

• IF Flash Recovery Area is enabled
• IF Flashback Database is enabled
• IF Oracle Managed Files are used

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Relevant INIT.ORA Parameters

• DB_RECOVERY_FILE_DEST_SIZE
• DB_RECOVERY_FILE_DEST
• DB_FLASHBACK_RETENTION_TARGET
• LOG_ARCHIVE_DEST_x
• LOG_ARCHIVE_DEST_1USE_FLASH_RECOVERY_AREA
• DB_CREATE_FILE_DEST
• DB_CREATE_ONLINE_LOG_DEST_x

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Usage for Flashback Database

• Flashback Database Logs
• Never backed in rman backup backup
• ONLY removed when no longer needed (or due to
  space constraints)

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Usage for RMAN Backups

• Restore archivelogs for recovery
• Automates removal or obsolete backups
• Automates removal of archivelog files

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Issues / Potential Problems

• Standby Database
• Can have different size Flash Recovery Area
• BUT need to recreate controlfile to change the
  redundancy from primary DB
• Space Management
• Not sure of which files will be on disk or not
• Known bugs

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Flashback Database
Production
Standby
Real time apply
Flashback Logs
Flashback Logs
Redo log
Redo log
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The End

• Thank you,
• Questions?
• babette_at_pythian.com

Babette Turner-Underwod The Pythian Group 2007
April
http//www.pythian.com/documents/flashrecoveryarea
.ppt