Wednesday, May 1, 2013

Oracle Recovery Manager (RMAN) Overview

In general, backup & recovery combines several strategies & procedures which are protecting database against data lose and reconstructing the database after any kind of data loss.

There are two types of backup strategies:
  1. Physical Backup – are backups of the physical files used in restoring &recovering database, such as datafiles, controlfiles and archived redo logs. 
  2. Logical Backup – contains logical data exported from database with oracle utilities (i.e, datapump) and stored in a binary file.

Physical backup is the foundation of any sound backup & recovery strategy. Logical backup is a useful supplement to physical backup but not ensure sufficient protection against data loss without physical backup. Unless otherwise specified, the term backup refers to physical backup.

Oracle provides two backup & recovery solutions –
  • Recovery Manager (RMAN) managed backup & recovery.
  • User managed backup & recovery.

RMAN can take backups of –
  1. Datafiles
  2. Controlfiles
  3. Redo logs / archived redo logs
  4. Serve parameter file (SPFiles)

A database recovery involved two tasks:
  • Restore- retrieve datafiles or controlfiles from backup.
  • Recover- apply archived & on-line redo log changes on restored datafiles ( it is also known as media recovery)
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