Data Protection and Backup System – SS3 Digital Technologies Lesson Note (First Term)

A backup is a copy of your data stored in a different place, so that you can recover your work if the original is lost through human error, hardware failure or malware. Related ideas include redundancy, which keeps systems running without stopping, and a disaster recovery plan, which tells a company what to do after a major disaster.

Behavioural objectives

By the end of the lesson, students should be able to:

• define data loss and backup, and state three causes of data loss;
• describe full, incremental and differential backups;
• explain the 3-2-1 rule;
• distinguish between backup and redundancy, and name two redundancy methods;
• explain a disaster recovery plan, RPO and RTO;
• list the steps for keeping a backup system healthy.

Why do we need backups?

Imagine you have spent three weeks typing your final project. Suddenly, your laptop falls, the screen goes black, and it will not turn on. Your work is gone. This is called data loss.

Data loss happens for three main reasons:

1. Human error: You accidentally hit “Delete” on the wrong folder.
2. Hardware failure: The hard drive inside the computer simply gets old and gets “tired.”
3. Malware: A virus or “ransomware” locks your files and demands money.

A backup is simply a copy of your data stored in a different place. It is like keeping a photocopy of your birth certificate in a different house. If the original gets lost, you are not in trouble.

What are the types of backup?

Not all backups are the same. Depending on how much data you have, you might choose one of these three:

• Full backup: You copy everything every single time.
  • Pros: Easy to find your files.
  • Cons: Takes a very long time and uses a lot of storage space.
• Incremental backup: You only copy what has changed since the last backup.
  • Pros: Very fast.
  • Cons: If you need to restore your data, you have to put all the “pieces” back together in order.
• Differential backup: You copy everything that has changed since the last full backup.

What is the 3-2-1 rule?

A professional rule of thumb is to have 3 copies of your data, on 2 different types of media (like a hard drive and a cloud drive), with 1 copy kept off-site (in a different building).

What is redundancy?

People often confuse backup with redundancy, but they are different. A backup is for when data is lost. Redundancy is for when you want to keep working without stopping.

Think of a car. A backup is the spare tyre in the boot. You have to stop the car, get out, and change it. Redundancy is like an aeroplane with two engines. If one engine fails, the plane does not fall; it keeps flying with the second one.

What are the common redundancy methods?

• RAID: This is a way of using multiple hard drives at once. If one drive crashes, the others already have the data and keep the computer running.
• Uninterruptible Power Supply (UPS): A big battery that keeps your server running even when the “NEPA” light goes out, giving you time to save your work.

What is disaster recovery?

A Disaster Recovery (DR) plan is a written document that tells a company exactly what to do if a major disaster happens, like a fire, a flood or a massive cyberattack. It is the set of instructions for what to do during an emergency.

It focuses on two main goals:

1. RPO (Recovery Point Objective): How much data are we willing to lose? (For example, “We can lose 4 hours of work, but not 24 hours.”)
2. RTO (Recovery Time Objective): How fast do we need to be back online? (For example, “The bank must be working again within 2 hours.”)

What is a recovery site?

Some big companies have a “hot site”, which is a second office in another city that is always ready. If the main office burns down, the staff just drive to the hot site, log in, and keep working.

How do we test and maintain a backup system?

The biggest mistake people make is “setting and forgetting.” You might think your computer is backing up every night, but if the cable is loose or the software has an error, you might find out too late that the backup is empty.

The golden rule: A backup is not a backup until you have successfully restored it.

Steps for a healthy system:

• Schedule: Set backups to happen automatically when you are asleep.
• Verification: Once a month, try to open a file from your backup to make sure it works.
• Physical security: Keep your backup drives in a fireproof safe or in the cloud.
• Rotation: Replace old hard drives every 3 to 5 years before they have a chance to fail.

Key points checklist

• Backup: A copy of data to prevent loss.
• Redundancy: Extra hardware to prevent “downtime.”
• 3-2-1 rule: A simple way to organise copies.
• DR plan: The instructions for what to do during an emergency.

Evaluation

1. What is data loss? State three causes.
2. Explain the difference between an incremental backup and a differential backup.
3. What does the 3-2-1 rule mean?
4. How is redundancy different from a backup? Give two examples of redundancy methods.
5. What do RPO and RTO stand for?

Assignment

1. Write a short note on the four steps for keeping a backup system healthy.
2. Explain what a Disaster Recovery plan is and why a company needs a hot site.