Importance of Database backup and recovery | full chapter

Database backup and recovery Overview:

What is database backup?

  • Keeping a secondary copy of the information from several locations.
  • Useful in case primary database crash or failure.
  • A way to protect and restore the database.

Why Backup?

  • In order to restore and recover the corrupted or damaged file for the continuous function of an application.

Who does it?

  • Generally, RDBMS or similar database management software does it.

How to recover? 

  • Database Administrator use backup files to restore the database to its operational state.

Difference between Backup and Archive.

Backup:

  • A secondary copy of the information.
  • Use for the recovery operation. Improve database availability by enabling the application to restore to a specific point in time.
  • Typically short term (Weeks or month).

 Archive:

  • A primary copy of the information.
  • Available for information retrieval.
  • Adds operational effectiveness by moving content out of the operating environment.
  • Typically long term (months, years, Decade)

Restoring and Recovery:

  • Process of copying backed up data from secondary storage to the original location.
  • Perform to return data that has been lost or damaged.
  • Operation is generally done after a crash, failure, or disaster.
  • The database gets recovered after restoring backed up files.

 Circumstances that lead to restoration.

  • Human error:- Data get accidentally deleted or damaged.
  • Power outage:- Removing unsaved files.
  • Malicious-attack:- Data theft, infected with the virus, hacking, etc.
  • Man-made or natural disaster.
  • Equipment, theft, malfunction, or failure.
  • Firmware corruption.

What is DBA and Responsibilities of Database Administrator

 Defining backup and recover strategy:

There are two ways to perform oracle database

  1. Oracle recovery manager (RMAN)
    • RMAN keeps backup.
    • RMAN is installed during the oracle server installation.

2. User managed backup and recovery:

    • Using OS command
    • Using SQL*PLUS commands.

 

Oracle recovery manager

RMAN

Backup and recovery consideration: 

  •   Business operational and technical consideration/
  •  Components of disaster recovery plans.
  •  Importance of testing backup and recovery strategy.

Responsibilities of DBA for maintaining recover-ability:

  • To keep the number of backup failures to a minimum, maximum data availability.
  • Spent less time in recovering, maximize recovery, recovery performance.
  • Minimize or avoid data loss, maximize data recover-ability.

 

Business Consideration:

  • Understand the business use of the system.
  • convince the system owners and management about the cost of maintaining system ability.
  • Cost assessment for maintaining availability.

 Components of the recovery plan:

  • What disaster recovery scenarios can occur on the system?
  • What disaster recovery scenarios involve recovery from data loss?
  • How volatile is data stored on the system ?
  • How quickly does the system need to be made available?
  • How does the cost providing a recovery strategy for any scenarios evaluated against the cost of losing time to re-enter the data? ?
  • The answers to these questions define the backup and recovery plan.

Importance of testing and backup recovery strategy:

  • What is the testing of backup recovery?
    • It is the process of accessing the effectiveness of software to replicate data for security and checking the ability to reliably retrieve data.
    • Backup and recovery testing is an essential part of the disaster recovery plan.

RDBMS Chapter