Backup Types Lecture Notes

Introduction

Fault Tolerance: Prevention of data loss if a component fails.
Disaster Recovery: Process of rebuilding an organization's data after a disaster.
Importance of backing up data even with fault tolerance measures.

Full Backup
- Backs up all the data.
- Simplest form of backup.
- Advantages:
  - Easy data restoration in one session.
- Disadvantages:
  - Takes the longest time to perform, especially with large data volumes.
Incremental Backup
- Backs up only the data that has changed since the last full or incremental backup.
- Example:
  - Full backup on Monday.
  - Incremental backups Tuesday through Friday: Tuesday’s data, Wednesday’s data, etc.
- Advantages:
  - Fastest backup method.
- Disadvantages:
  - Longest to restore because restoration requires:
    - The full backup.
    - All incremental backups in order.
Differential Backup
- Backs up data changed since the last full backup.
- Example:
  - Full backup on Monday.
  - Differential backups Tuesday through Friday:
    - Tuesday’s data.
    - Wednesday’s data includes Tuesday’s.
    - Thursday’s data includes Tuesday’s and Wednesday’s, etc.
- Advantages:
  - Faster than a full backup.
- Disadvantages:
  - Slower than an incremental backup.
  - Requires the last full backup and the last differential backup for restoration.

Full Backup:
- Backs up all data.
- Longest to perform.
- Fastest to restore with only the full backup needed.
Incremental Backup:
- Backs up data changed since last backup.
- Fastest backup.
- Slowest to restore due to the need to restore in order.
Differential Backup:
- Backs up data changed since last full backup.
- Faster than full backup, slower than incremental.
- Restoration requires full backup and last differential backup.
- Restore time is between full and incremental.