System backup strategies in SCADA systems - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a full backup in system backup strategies?

A full backup copies all data from the system to a backup location. It is the complete snapshot of the system at a point in time.

beginner

Explain incremental backup.

An incremental backup saves only the data that has changed since the last backup, whether full or incremental. It is faster and uses less storage.

intermediate

What is the main advantage of differential backup over incremental backup?

Differential backup copies all changes since the last full backup, making restoration faster because only the full backup and the latest differential are needed.

beginner

Why is regular testing of backups important?

Testing backups ensures that data can be restored successfully when needed. It prevents surprises during emergencies and confirms backup integrity.

beginner

Name two common storage locations for backups in SCADA systems.

Backups can be stored on external hard drives or network-attached storage (NAS). Cloud storage is also an option if security policies allow.

Which backup type copies all data every time it runs?

A Full backup

B Incremental backup

C Differential backup

D Snapshot backup

A full backup copies all data each time it runs, unlike incremental or differential backups.

What does an incremental backup save?

A Only system configuration files

B All data since last full backup

C Only data changed since last backup

D A complete system image

Incremental backup saves only data changed since the last backup, making it efficient.

Why might differential backups be preferred over incremental backups?

A They use less storage space

B They simplify restoration by needing fewer backup sets

C They are faster to create

D They backup only system files

Differential backups simplify restoration because only the full backup and latest differential are needed.

What is a key reason to test backups regularly?

A To free up storage space

B To speed up backup process

C To update backup software

D To ensure data can be restored successfully

Testing backups confirms that data restoration works when needed.

Which of these is NOT a common backup storage option for SCADA systems?

A Temporary RAM memory

B Network-attached storage (NAS)

C Cloud storage (if allowed)

D External hard drives

Temporary RAM memory is volatile and not suitable for backup storage.

Describe the differences between full, incremental, and differential backups.

Think about how much data each backup saves and how that affects storage and restoration.

Explain why backup testing is critical in system backup strategies.

Imagine needing to restore data and finding backups don't work.

Practice

1. What is the main purpose of creating system backups in SCADA systems?

easy

A. To save copies of important data to prevent loss

B. To speed up the system performance

C. To increase the number of users

D. To reduce the power consumption

Solution

1. Step 1: Understand the role of backups

   Backups are copies of data saved to protect against data loss.

2. Step 2: Identify the main goal in SCADA context

   In SCADA systems, backups prevent loss of critical control data and configurations.

3. Final Answer:

   To save copies of important data to prevent loss -> Option A

4. Quick Check:

   Backup purpose = prevent data loss [OK]

Hint: Backups protect data from loss or damage [OK]

Common Mistakes:

• Thinking backups improve speed
• Confusing backups with user management
• Assuming backups reduce power use

2. Which command syntax correctly creates a compressed backup archive of the /etc/scada directory using tar?

easy

A. tar -cfz /etc/scada backup.tar.gz

B. tar -xf backup.tar.gz /etc/scada

C. tar -cz /etc/scada backup.tar.gz

D. tar -czf backup.tar.gz /etc/scada

Solution

1. Step 1: Understand tar options

   -c creates archive, -z compresses with gzip, -f specifies filename.

2. Step 2: Match correct order and options

   tar -czf backup.tar.gz /etc/scada uses correct order: tar -czf backup.tar.gz /etc/scada

3. Final Answer:

   tar -czf backup.tar.gz /etc/scada -> Option D

4. Quick Check:

   Correct tar syntax = -czf [OK]

Hint: Use -czf to create compressed tar archive [OK]

Common Mistakes:

• Using -xf which extracts instead of creates
• Wrong option order like -cfz
• Placing filename after directory incorrectly

3. Given the command rsync -av /scada/data/ /backup/scada_data/, what will be the result?

medium

A. It deletes all files in /backup/scada_data

B. It copies all files from /scada/data to /backup/scada_data preserving attributes

C. It compresses files in /scada/data into a zip archive

D. It moves files from /backup/scada_data to /scada/data

Solution

1. Step 1: Understand rsync options

   -a means archive mode (preserves attributes), -v means verbose output.

2. Step 2: Analyze source and destination paths

   Command copies files from /scada/data/ to /backup/scada_data/ preserving file info.

3. Final Answer:

   It copies all files from /scada/data to /backup/scada_data preserving attributes -> Option B

4. Quick Check:

   rsync -av copies with attributes [OK]

Hint: rsync -av copies files with attributes [OK]

Common Mistakes:

• Confusing rsync with delete command
• Thinking it compresses files
• Mixing source and destination paths

4. You run tar -czf backup.tar.gz /scada/config but the backup file is empty. What is the likely cause?

medium

A. The /scada/config directory does not exist or is empty

B. The tar command syntax is incorrect

C. The backup file is corrupted after creation

D. The system lacks gzip compression support

Solution

1. Step 1: Check directory existence

   If /scada/config does not exist or is empty, tar creates an empty archive.

2. Step 2: Verify command syntax and system support

   Command syntax is correct and gzip is standard; corruption unlikely immediately after creation.

3. Final Answer:

   The /scada/config directory does not exist or is empty -> Option A

4. Quick Check:

   Empty archive = missing or empty source directory [OK]

Hint: Check source directory exists and has files [OK]

Common Mistakes:

• Assuming syntax error without checking directory
• Blaming gzip support without evidence
• Ignoring possibility of empty source

5. You want to automate daily backups of SCADA system data to a remote server using rsync over SSH. Which command correctly achieves this?

hard

A. tar -czf /backup/scada_data.tar.gz /scada/data/

B. rsync -av /scada/data/ /backup/scada_data/

C. rsync -avz -e ssh /scada/data/ user@remote:/backup/scada_data/

D. scp /scada/data/ user@remote:/backup/scada_data/

Solution

1. Step 1: Identify remote backup with encryption

   rsync with -e ssh uses SSH for secure remote transfer.

2. Step 2: Confirm options for compression and archive

   -a for archive, -v for verbose, -z for compression; source and remote destination are correct.

3. Final Answer:

   rsync -avz -e ssh /scada/data/ user@remote:/backup/scada_data/ -> Option C

4. Quick Check:

   rsync + ssh + compression = secure remote backup [OK]

Hint: Use rsync with -e ssh for secure remote backups [OK]

Common Mistakes:

• Using local backup command for remote backup
• Using scp without rsync's efficiency
• Omitting SSH option for remote transfer