← VCE Data Analytics U4O2

Backup storage locations and the 3-2-1 rule

Keep 3 copies of data on 2 different types of media, with 1 copy stored offsite (such as cloud storage), so one disaster cannot destroy both the data and its backups.

Part of: VCE Data Analytics - U4O2 - Cyber Security: Data Security — Module 87, QCE Digital Solutions Unit 4 — Complex Digital Data Exchange Problems and Solution Requirements — Module 56, WA Computer Science ATAR Year 11 — Network Communications — Module 143, WA Computer Science ATAR Year 11 — Cyber Security — Module 129

Understanding Backup storage locations and the 3-2-1 rule in VCE Data Analytics U4O2

What it does: Storing the original and the backup together means one disaster affects both, which is the weakness of onsite-only backups. This setup gives 3 copies on 2 media types (local drive and cloud), with the cloud copy offsite. A backup in a separate location is not affected by a disaster at the office. A drive in the same office can be destroyed by the same fire. The 1 is the offsite copy. It makes sure a disaster at the main location cannot destroy every copy of the data. Separating the backup from the original location is the core idea of the 3-2-1 rule.

Common mistakes: The 3-2-1 rule starts with 3 copies of the data, not 2. The line should be rule_copies = 3. A flood in the office would destroy onsite backups stored in the same building. That is why an offsite copy is needed. The line should be onsite_backups = 'destroyed'.

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This module's key terms are also in a printable crossword (Modules 80–113) and word search (Modules 44–113).

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Learning
Duo
A school keeps its nightly backup on a drive in the same server room as the original data. A fire hits that room. What is the problem?
Nothing is lost, because a backup always survives any disasterBoth the data and the backup are lost, because the backup was stored onsite
Matches
Original data + backup on the same server, both in the office
↓
Both copies sit in the same location on the same device, so one disaster or hardware failure destroys the data and its backup. Keep at least one copy offsite, such as cloud storage.
Applying
Meanings
Term
3-2-1 rule
Meaning
Keep 3 copies of data on 2 different types of media, with 1 copy stored offsite (such as cloud storage), so one disaster cannot destroy both the data and its backups.
Practice
IF copies >= 3 AND media >= 2 AND offsite >= 1 THEN
Testing
Gaps
3-2-1 rule: copies of the data
Check Answer
Spots
1rule_copies = 2
2rule_media = 2

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Quick Questions

1. A school keeps its nightly backup on a drive in the same server room as the original data. A fire hits that room. What is the problem?
A. Nothing is lost, because a backup always survives any disaster
B. Both the data and the backup are lost, because the backup was stored onsite ✓
Onsite backups share the same location as the original data, so one disaster such as a fire or flood can destroy both. Keeping a copy offsite avoids this.
2. Which storage location best protects a backup from a fire at the main office?
A. A second hard drive in the same office
B. Offsite or cloud storage in a different location ✓
A backup in a separate location is not affected by a disaster at the office. A drive in the same office can be destroyed by the same fire.
3. What does the 3-2-1 rule say?
A. 3 copies of data, on 2 types of media, with 1 copy offsite ✓
B. 3 offsite sites, 2 passwords, and 1 backup per week
The 3-2-1 rule means 3 copies in total, stored on 2 different media types, with 1 of those copies kept offsite.
4. In the 3-2-1 rule, what does the '1' stand for?
A. One copy stored offsite, such as in cloud storage ✓
B. One copy stored on the same server as the original
The 1 is the offsite copy. It makes sure a disaster at the main location cannot destroy every copy of the data.
5. A business has its original data plus one backup on an external hard drive. Does it follow the 3-2-1 rule?
A. No. It has only 2 copies, on 1 type of media, and none offsite ✓
B. Yes. Having any backup at all meets the 3-2-1 rule
The rule needs 3 copies, 2 media types and 1 offsite copy. Original plus one external drive meets none of these requirements.

Match the Pairs

3-2-1 rule → Keep 3 copies of data on 2 different types of media, with 1 copy stored offsite so one disaster cannot destroy everything.
Offsite backup → A copy of data stored at a different physical location, such as cloud storage or another building, so a fire or flood at the main site does not destroy it.
Backups kept only onsite are at risk because a single fire or flood could destroy both the original data and its copies. → Server room + backup drive in same room = onsite only
A plan that follows the 3-2-1 rule has 3 copies, on 2 types of media, with 1 copy kept offsite such as in the cloud. → Original + external drive + cloud backup
Original data + backup on the same server, both in the office → Both copies sit in the same location on the same device, so one disaster or hardware failure destroys the data and its backup. Keep at least one copy offsite, such as cloud storage.
3 copies of data, all saved on external hard drives in the office → There are 3 copies but only 1 media type and no offsite copy. The 3-2-1 rule needs 2 different media types and 1 copy stored offsite, for example in the cloud.

Key Term

3-2-1 rule
Keep 3 copies of data on 2 different types of media, with 1 copy stored offsite (such as cloud storage), so one disaster cannot destroy both the data and its backups.

Fill in the Blanks

1. 3-2-1 rule: 3 copies of the data
Hint: Type the total number of copies the rule requires (the first number in the rule).
2. 3-2-1 rule: 2 different types of media
Hint: Type how many different storage media types the rule requires (the middle number).
3. 3-2-1 rule: 1 copy stored offsite
Hint: Type the one-word term for a location away from the main site.
4. Backup in same building as data = onsite
Hint: Type the one-word term for a backup kept in the same location as the original data.
5. A fire hits the office; onsite copies fail Keep 1 copy in cloud storage
Hint: Type the kind of internet-based storage that keeps a copy safe from a local disaster.

Spot the Error

Question 1
A rule_copies = 2
B rule_media = 2
C rule_offsite = 1
Line A — The 3-2-1 rule starts with 3 copies of the data, not 2. The line should be rule_copies = 3.
Question 2
A disaster = 'office flood'
B onsite_backups = 'safe'
C offsite_backup = 'safe'
D print(offsite_backup)
Line B — A flood in the office would destroy onsite backups stored in the same building. That is why an offsite copy is needed. The line should be onsite_backups = 'destroyed'.
Question 3
A copies ← 3
B IF copies > 3 THEN
C DISPLAY 'Add a backup'
D END IF
Line B — The warning to add a backup should appear when there are fewer than 3 copies. The broken line used > instead of <. It should be IF copies < 3 THEN.
Question 4
A copies ← 3
B media ← 2
C offsite ← 1
D rule_met ← offsite = 0
Line D — The rule needs at least 1 offsite copy. Having 0 offsite copies means the rule is not met. It should be rule_met ← offsite >= 1.
Question 5
A media = ['disk', 'cloud']
B copies = 3
C if len(media) <= 1:
D print('Media rule met')
Line C — The 3-2-1 rule needs at least 2 different types of media. The test should be len(media) >= 2, not <= 1, which would pass with only one media type.

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