System backup strategies in SCADA systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Full vs Incremental Backups

Which statement correctly describes the difference between a full backup and an incremental backup in a SCADA system?

A Full backups copy only configuration files, incremental backups copy only runtime data.

B An incremental backup copies all data every time, while a full backup copies only data changed since the last backup.

C Both full and incremental backups copy all data every time but store it differently.

D A full backup copies all data every time, while an incremental backup copies only data changed since the last backup.

💡 Hint

Think about how much data each backup type copies each time.

Full backups copy all data regardless of changes. Incremental backups copy only data changed since the last backup, saving time and space.

💻 Command Output

intermediate

Backup Command Output Interpretation

Given the SCADA system backup command output below, what does it indicate?

Backup started at 02:00
Files copied: 1500
Files skipped: 300
Backup completed successfully in 45 minutes

A The backup copied 1500 files and skipped 300 files, finishing without errors.

B The backup failed because 300 files were skipped.

C Only 300 files were copied, 1500 were skipped.

D The backup took 300 minutes to complete.

💡 Hint

Skipped files usually mean unchanged files not copied again.

The output shows 1500 files copied and 300 skipped, meaning unchanged files were not copied again. The backup finished successfully in 45 minutes.

🔀 Workflow

advanced

Backup Schedule Configuration

You need to configure a SCADA system to perform a full backup every Sunday at 3 AM and incremental backups Monday through Saturday at 3 AM. Which cron schedule correctly implements this?

A 0 3 * * 0-6 /backup/full.sh

B

0 3 * * 0 /backup/incremental.sh
0 3 * * 1-6 /backup/full.sh

C

0 3 * * 0 /backup/full.sh
0 3 * * 1-6 /backup/incremental.sh

D 0 3 * * 1-7 /backup/incremental.sh

💡 Hint

Remember Sunday is day 0 in cron and scripts must run at 3 AM.

Cron '0 3 * * 0' runs full backup Sundays at 3 AM; '0 3 * * 1-6' runs incremental backups Monday to Saturday at 3 AM.

❓ Troubleshoot

advanced

Diagnosing Backup Failure

A SCADA system backup script fails with the error: 'Permission denied: cannot write to /backup/storage'. What is the most likely cause?

A The backup storage directory is full but permissions are correct.

B The backup storage directory has incorrect permissions preventing write access.

C The network connection to the backup server is down.

D The backup script syntax is incorrect causing failure.

💡 Hint

Permission denied errors usually relate to access rights.

The error indicates the script cannot write to the directory due to permission issues, so directory permissions need fixing.

✅ Best Practice

expert

Optimal Backup Strategy for SCADA Systems

Which backup strategy best balances data safety and system performance for a critical SCADA system with 24/7 uptime?

A Perform daily incremental backups with weekly full backups during low-activity hours, plus offsite storage of backups.

B Only perform full backups monthly to reduce system load.

C Perform full backups every hour to ensure all data is saved frequently.

D Rely solely on real-time replication without backups.

💡 Hint

Consider backup frequency, system load, and disaster recovery.

Daily incremental and weekly full backups during low-activity hours reduce load while ensuring data safety. Offsite storage protects against site disasters.