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DBA: Backups

DBA: Backups. Agenda. Define backup Discuss Backup Terminology Explain various backup and restore options in Oracle Demonstrate backups in Oracle. Question: What is a Backup?. Backup. A procedure for making extra copies of data for the purpose of restoration in case of loss or damage.

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DBA: Backups

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  1. DBA: Backups

  2. Agenda Define backup Discuss Backup Terminology Explain various backup and restore options in Oracle Demonstrate backups in Oracle

  3. Question: What is a Backup?

  4. Backup A procedure for making extra copies of data for the purpose of restoration in case of loss or damage. Guide to Oracle 10g

  5. Backup Terminology • Hot Backup • Cold Backup • Full Backup • Incremental Backup • Differential Backup • Backup Window • Backup Job • On-line • Off-line • Off-Site • Data Compression • Data Deduplication • Data Encryption

  6. Types of Backup A full backup (level 0) is a complete copy of a partition. An incremental backup (level 1) is an archive of only the files that have changed since the last full backup. A differential backup (level 2, 3, etc) is an archive of only the file that have changed since the last backup (not necessarily full backup. Guide to Oracle 10g

  7. Short-Sighted Backups – Why? • Why are each of these a bad backup strategy? Advantages / Disadvantages? • Only taking Cold, Full Backups • One Full Offsite backup • Just hot backups • Full backups monthly, differentials daily. Guide to Oracle 10g

  8. Let’s Talk Strategy • Ideally we’d like to backup everything all the time and keep it around forever. • Realistically, we cannot do that. • You need a combination of short-term and long-term strategies. For example: • At least 3 copies of the data, 1 off site. • Hot backups for convince, cold backups for insurance D/R. • Test your restore process, at multiple levels. • Others?

  9. Database Backup and Recovery • Important database administration support tasks include: • Backup • Offline/cold • Online/hot • Recovery • Restore Entire tablespaces • Build test / dev environments from restores • Recover missing / erroneous data in tables.

  10. Creating Offline (Cold) Backups • Shut down database instance • Copy specific database files to alternate disk location • Parameter file • Control files • Datafiles • Not redo logs • Restart database instance

  11. Creating Online (Hot) Backups • Place database instance in ARCHIVELOG mode • Back up control file • Back up datafiles • Instruct database to write current contents of redo log files to archive files - Create backup copies of archive log files Guide to Oracle 10g

  12. Database Recovery • Process of restoring database from either cold or hot backup files • Necessary after database failure • Cold backup recovery: • Shut down database • Restore backed up control file and datafiles to database server • Restart database

  13. Database Recovery (continued) • Hot backup recovery: • Recover database to point at which last hot backup created • Use control trace file to generate new copy of control file • Restore backup copies of datafiles • Perform media recovery Guide to Oracle 10g

  14. Demo – Start and Stop Oracle Let’s use OEM to start and stop your Oracle instance, then create a cold backup Guide to Oracle 10g

  15. Oracle Backup Strategies • Cold backups • Simplest to perform • Satisfactory for databases whose: • Contents do not change very much • Users can tolerate downtime while DBA creates cold backup files • Hot backups • Complex to perform • Better suited for dynamic, mission-critical databases • If you setup a clustered environment you can perform cold backups without loss of service.

  16. Questions

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