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Navigating the Oracle Backup Maze. Robert Spurzem Senior Product Marketing Manager Agenda. How important is backup speed? RAW vs. cooked? Logical backups using Export utility RMAN vs. Alter Tablespace? Offline vs. online? Full vs. incremental? Snapshots?

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navigating the oracle backup maze
Navigating the Oracle Backup Maze

Robert Spurzem

Senior Product Marketing Manager

  • How important is backup speed?
  • RAW vs. cooked?
  • Logical backups using Export utility
  • RMAN vs. Alter Tablespace?
  • Offline vs. online?
  • Full vs. incremental?
  • Snapshots?
  • Backup to Disk?
  • Future Trends
how important is backup speed
How important is backup speed?
  • Speed is important to meet the backup window
  • Speed is dependent on network bandwidth, devices and cpu
  • Vendor benchmarks aren’t real world configurations
  • Oracle RMAN is not the bottleneck
  • Databases greater than 200G – media servers are recommended
  • Restore needs to be tested for speed
    • 50G can take over 20 hrs if device and operational problems occur
raw vs cooked
RAW vs. cooked?
  • This is an application decision
  • RAW is fast but requires more management
  • File systems have more overhead but are easier to manage and backup
    • VxFS Quick I/O product has advantages
  • Makes no difference to RMAN
    • RMAN backs up from RAW or Cooked
    • RMAN restores from RAW or Cooked
    • RMAN can restore from RAW to Cooked or from Cooked to RAW
logical backups using export utility
Logical backups using Export utility
  • Export utility is provided with Oracle database and is easy to use
    • Does not require purchase of a module or agent product
  • Export examines every data block for consistency
  • Export backs up to disk so recovery can be fast
    • Export can restore by table within a tablespace
    • Can only recovery to a single point-in-time
  • Export takes longer than a physical backup
  • Full Export requires database to be in RESTRICT mode for intertable consistency
    • No database access during backup
rman vs alter tablespace
RMAN vs. Alter Tablespace?
  • ALTER TABLESPACE BEGIN online backup
    • Custom scripting required
    • Issue with fractured blocks
    • Freezes the data file header
    • Records the end of backup in the SCN header
    • Forces redo logs with recovery from the time of the backup
    • The redo logs fill faster with the full block changes, not the vector changes
    • Archiving means the online redo logs will continue to fill and archive logs will be used – must manage disk space.
rman vs alter tablespace7
RMAN vs. Alter Tablespace?
  • RMAN online backup
    • Introduced with Oracle 8
      • Five years of improvements
      • 50% use and growing
    • No fractured block issue
      • Reads the Oracle block size not the file system block size
      • Normal operation for redo logs
    • Reduces complexity
    • Efficient backup to tape
    • Multiple device streaming
    • Improvements with Oracle9i R2
      • Persistent Parameter Configuration
      • Restartable backup and restore
      • Self Describing Backup
offline vs online backups
Offline vs. online backups?
  • All depends on the db usage and activity
    • Can you shut down the db and for how long?
  • Can the backup be completed within the backup window?
  • No database access during offline backup
  • Database server is burdened with two processes during online backup
  • Archive log space management is required during online backup if the database is archiving
full vs incremental backups
Full vs. incremental backups?
  • Full Oracle backups are the norm no question
    • Perform full backups once a day
    • Backup the archive redo log files every 4 hours
  • Incremental backups performed by RMAN have well known deficiencies
  • Incrementals read the entire database to find the changed blocks
  • Incrementals have a difficult time streaming the tape device
are you a candidate for snapshots
Are you a candidate for snapshots?
  • What is a snapshot?
    • Frozen image backup from physical mirror or logical snapshot
  • Do you require fast recovery? (<2 hours)
  • Does your database need to be up 24x7; 80% utilization; no backup window
  • For very large databases >500G that are larger than backup window
  • RMAN Proxy Backup API
  • Array based vs. host based snapshots?
  • Are snapshots more complex?
are you a candidate for backup to disk
Are you a candidate for backup to disk?
  • The cost of disk is dropping
    • $1M/TB -> $100K/TB -> $10K/TB -> $1K/TB
    • New ATA drives are the driving factor
  • What are the advantages of backing up to disk?
    • Faster backup and faster recovery
  • What are the disadvantages?
    • Adds a second backup process
  • Tape backup still required for disaster recovery and archival
  • Adds potential complexity and management overhead
  • Potential for longer recovery times from tape
    • Single-step vs. Two-step recovery
future trends
Future trends
  • Full data life cycle management
    • Automation of entire information protection
    • Using snapshots; disk backup; tape archiving
    • Snapshot management
  • Efficient block level data protection
    • Faster backups and restores
    • Reduce media costs
  • Ease of management
    • Wizards to speed configuration and guide recovery
    • Automatic performance tuning