Database backup and recovery | full chapter

Overview:

What is database backup ?

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

Why to Backup ?

  • In order to restore and recover the corrupted or damaged file for 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 database to its operational state.

Difference between backup and Archive.


Backup:
  • A secondary copy of information.
  • Use for recovery operation. Improve database availability by enabling application to restore to a specific point in time.
  • Typically short term (Weeks or month).
 Archive:
  • Primary copy of information.
  • Available for information retrieve.
  • Adds operational effectiveness by  moving content out of operation environment.
  • Typically long term (months, years, Decade)

Restoring and Recovery:

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

 Circumstances that leads to restoration.

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

 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 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 number of backup failure to 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 business use of system.
  • convince system owner and management about the cost of maintaining system ability.
  • Cost assessment for maintaining availability.

 Components of 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 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 loosing time to re-enter the data. ?
  • The answers of these questions defines the backup and recovery plan.
 Importance of testing and backup recovery strategy:
  • What is testing of backup recovery ?
    • It is the process of accessing the effectiveness of an software to replicate data for security and checking the ability for reliably retrieve data.
    • Backup and recovery testing is an essential part of disaster recovery plan.   


Database backup and recovery | full chapter Database backup and recovery | full chapter Reviewed by Santosh Adhikari on February 03, 2019 Rating: 5

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