Course 4 – System Administration and IT Infrastructure Services

Week 5: Data Recovery & Backups

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In the fifth week of this course, we’ll learn about data recovery and backups. In any tech role, it’s important to know how to backup and recover data — it’s even more important for system administration. We will also learn about common corporate practices like designing a disaster recovery plan and writing post-mortem documentation. By the end of this module, you’ll know the tradeoffs between on-site and off-site backups, understand the value and importance of backup and recovery testing, know different options for data backup (as well as the risks) and understand the purpose and contents of a disaster recovery plan.

Learning Objectives

  • Understand tradeoffs between on-site vs off-site backups
  • Understand what characteristics to evaluate when designing a backup system
  • Understand the value and importance of backup and recovery testing
  • Understand the different options for data backup and the risks that each one protects against
  • Understand the purpose and contents of a disaster recovery plan


1. How can you recover from an unexpected data loss event? Check all that apply.

  • Write a post-mortem report.
  • Recover data from damaged devices. (CORRECT)
  • Restore data from backups. (CORRECT)
  • Design a disaster recovery plan.

Nice job! If a hard drive or device becomes damaged or fails, you can attempt to recover data using specialized software. If data becomes corrupt or gets deleted, you can also restore the data from backup.

2. Where is it best to store backups, physically?

  • On-site
  • Off-site
  • In a safe
  • Across multiple locations (CORRECT)

Yep! Ideally, backups should be stored in multiple physical locations to reduce the risk of a catastrophe causing you to lose your backups. Typically, data would be backed up somewhere locally, and the backups would be replicated and stored off-site.

3. Which of these should be included in your backups? Check all that apply.

  • Firewall configurations (CORRECT)
  • A downloads folder
  • Family vacation photos
  • Sales databases (CORRECT)

Great work! Critical data for an organization, like firewall configs and relevant databases, should be included in the backup plans.

4. What’s magnetic tape backup media best suited for?

  • Long-term archival data  (CORRECT)
  • Low-latency cached data
  • Cheap backup systems
  • Quick and efficient backups

That’s correct! Magnetic tape media is very cheap, but it’s also super slow and inconvenient to retrieve data from. This makes it a good option for archiving old data that won’t be needed often.

5. Why is it important to test backups and restoration procedures? Check all that apply.

  • To reduce the size of backup data
  • To speed up the backup-and-restore process
  • To ensure backups work and data can be restored from them (CORRECT)
  • To ensure that relevant data is included in the backups (CORRECT)

Excellent! It’s super important to test backups and restore procedures to ensure that they actually work! Backup archives could be corrupt or inconsistent, preventing proper restoration. Restore procedures are just as important to test, to ensure that critical data can be extracted from backups if a disaster strikes. Disaster testing can also reveal any gaps in your backup coverage without risking real-world data loss.

6. Which of the following backup types are most space-efficient?

  • Full backups
  • Differential backups
  • Incremental backups (CORRECT)

Wohoo! Incremental backups are the most efficient. While they start with a full backup, on subsequent runs, they only backup the parts of files that have changed since the last run.

7. True or false: You can use a RAID array and use rsync to copy critical data to it for backups.

  • True
  • False (CORRECT)

You got it! RAID isn’t a replacement for a backup system. You may use a RAID array as a storage system in your backup server, but copying files to a RAID array won’t protect against data corruption or data deletion.


1. What elements should a disaster recovery plan cover? Check all that apply.

  • Detection measures (CORRECT)
  • Preventative measures (CORRECT)
  • Recovery measures (CORRECT)
  • Drastic measures (CORRECT)

That’s right! A disaster recovery plan shouldn’t only have recovery procedures; it should include detection measures so that you can be made aware of an incident, along with preventative measures to help avoid a disaster in the first place.

2. Why are detection measures included in a disaster recovery plan?

  • They aren’t
  • Because it’s important to know when a disaster occurs (CORRECT)
  • Because they prevent data loss
  • Because they make recovering from data loss easier

Awesome! The sooner you can be alerted that an incident is going on, the quicker you can take measures to stop it.

3. What are good preventative measures to incorporate in your organization? Check all that apply.

  • Monitoring and alerting systems
  • Redundant systems (CORRECT)
  • Regular backups (CORRECT)
  • Accessible and up-to-date documentation (CORRECT)

You got it! Good documentation is considered a preventative measure, since it can avoid costly mistakes and make handling outages or system failures easier.

4. What are good detection measures to incorporate in your organization? Check all that apply.

  • Environmental monitoring (CORRECT)
  • Backing up firewall rules
  • Redundant power supplies
  • System performance monitoring (CORRECT)

Nice job! Monitoring the environmental conditions in a server room will alert you if things might cause problems for your equipment. System performance monitoring can also alert you to anomalies in requests or traffic to a server.

5. What are good recovery measures to incorporate in your organization? Check all that apply.

  • Restoring server configs from backup (CORRECT)
  • Following detailed recovery plan documentation (CORRECT)
  • Monitoring for internet line outages
  • Maintaining redundant servers

Correct! Maintaining backups of server configs will make restoring a damaged system much quicker and easier. Detailed documentation on how exactly to do this will also speed up this process.


1. What’s the intent behind writing a post-mortem?

  • To assign blame for mistakes 
  • To assign legal liability
  • To learn from mistakes and improve in the future (CORRECT)
  • To scare people into avoiding risky behavior

Yep! A post-mortem is meant to analyze what happened around an incident to identify what went wrong so it can be avoided in the future.

2. What should the timeline in a post-mortem include? Check all that apply.

  • Actions taken before, during, and after the event
  • A detailed analysis of the incident, including root cause and scope
  • Detailed dates and times (CORRECT)
  • A summary of the incident and how long it lasted

That’s right! The timeline should include actions taken leading up to, during, and after the incident, along with the dates and times when these actions were taken.


1. What’s the optimal recommended backup storage strategy?

  • On-site backups
  • Off-site backups
  • A combination of on- and off-site backups (CORRECT)
  • Tape backups

Yep! Ideally, backups would be stored both on- and off-site to reduce the chances of all your backups being wiped out in a disaster.

2. How can you verify that your disaster recovery plan will be effective? Check all that apply.

  • Through thorough testing (CORRECT)
  • By waiting for a disaster
  • Through disaster simulations (CORRECT)

Excellent! Testing various aspects of your recovery plan will ensure that the documented procedures will work as they’re designed. This testing can be accomplished by simulating disasters and having teams run through documented procedures.

3. What’s the purpose of a post-mortem report?

  • To learn from mistakes (CORRECT)
  • To test systems
  • To identify those in the wrong
  • To assign legal liability

Yep! A post-mortem report is designed to analyze an event in order to learn from mistakes.

4. What is the single most important part of data recovery?

  • Creating power redundancies
  • Effectively backing up data (CORRECT)
  • Port forwarding
  • Stocking replacement drives

You got it! One of the most important techniques you’ll learn is how to effectively back up your data. Disaster plans should involve making regular backups of any and all critical data that’s necessary for your ongoing business processes. Without data to recover, data recovery can’t take place!

5. What are advantages of on-site backups? Check all that apply.

  • There is less bandwidth usage. (CORRECT)
  • There is quicker data access. (CORRECT)
  • Data is more secure because of less outbound traffic. (CORRECT)
  • Data is safe in case of disaster.

Well done! Less outbound bandwidth will be used if you aren’t backing up off-site.

Well done! One advantage of on-site backup solutions is that the data is physically very close, which makes accessing the data much quicker.

Well done! The more traffic going out of the network, even for backups, the higher the risk of data being intercepted. On-site backups reduce this vulnerability.

6. Which of these are common backup tools you might consider when designing a backup solution? Check all that apply.

  • Regedit
  • Backup and Restore (CORRECT)
  • Time Machine (CORRECT)
  • Rsync (CORRECT)

Nice job! Microsoft provides a first-party solution called Backup and Restore. Backup and Restore supports multiple modes including complete, incremental, and differential backups.

Nice job! Apple’s first-party backup software is called Time Machine. Time Machine mainly supports an incremental backup mode.

Nice job! Rsync is commonly used as a backup tool. It can be used for simple automated backups, and supports compression and SSH. Its main function is transfering files between computers.

7. Cloud services are the ideal backup option for user files. Which of these is not one of today’s popular cloud storage platforms?

  • Rsync (CORRECT)
  • Dropbox
  • Apple iCloud
  • Google Drive

You got it! Rsync is a command line tool used to compress and transfer files from one computer to another. While it is often used for backup, it’s not a cloud service.

8. Which of these are components of a post-mortem report? Check all that apply.

  • Detailed timeline of key events (CORRECT)
  • All log data
  • Explanation of resolution and recovery efforts (CORRECT)
  • Brief summary (CORRECT)

You got it! This should include everything that happened throughout the event, like when it started, and when people involved were notified or realized what was going on. Every action taken in an attempt to resolve the situation should also be identified. Time and dates should be noted.

Nice job! The report should detail about what steps were taken to recover, the rationale and reasoning behind those actions, and what the outcome of each step was. Including the rationale gives those reading the report more context on how the event played out.

Right on! A short paragraph to summarize the incident should be written first. It should include what the incident was, how long it lasted, what the impact was, and how it was fixed.

9. What types of backup schemes are available? Check all that apply.

  • Full backup (CORRECT)
  • Differential backup (CORRECT)
  • Incremental backup (CORRECT)
  • Partial backup

Wohoo! A full backup makes a copy of all files on each run. A differential backup starts with a full backup and only backs up changed files on each subsequent run. An incremental backup also begins with a full backup, but only backs up the portions of files that have changed on future runs.

10. What are some ways you can make your backups more space-efficient? Check all that apply.

  • Use full backups only
  • Use compression (CORRECT)
  • Use encryption
  • Use incremental backups (CORRECT)

That’s exactly right! Compression reduces the overall size required to store the backup data, making it more efficient. Incremental backups only store the data that’s changed, as opposed to all data or files, making it more efficient, too.

11. Which backup type only backs up files that have changed since the last run?

  • Full backup
  • Differential backup (CORRECT)
  • Incremental backup
  • Partial backup

You nailed it! A differential backup only saves files that have changed since the last run.

12. Which is an advantages of off-site backups?

  • Data is safe in case of disaster. (CORRECT)
  • There is quicker data access.
  • Data is more secure because of less outbound traffic.
  • There is less bandwidth usage.

Great work! In the event of a disaster, any on-site backups risk being lost. Storing backups off-site creates physical redundancy for your data.

13. Which type of backup only saves copies of files that have been changed or created since the last backup?

  • RAID array
  • Complete backup
  • Differential backups (CORRECT)
  • Incremental backup

Right on! The advantage of a differential backup is that you aren’t storing backups of duplicated, unchanging data. It is a more efficient approach to only back up files that have changed or been created since the last full backup.

14. Which backup method saves copies of all important files and data at each backup?

  • RAID array
  • Complete backup (CORRECT)
  • Incremental backup
  • Differential backups

Well done! You can do a complete backup on a regular basis, which involves making a copy of the data to be backed up. The full, unmodified contents of all files is included in this backup mechanism, whether the data was modified or not. This is often very inefficient, if done often with unchanging files.

15. A disaster recovery plan is a collection of documented procedures and plans on how to react and handle an emergency or disaster scenario from an operational perspective. What are important elements of a disaster recovery plan? Check all that apply.

  • Disciplinary measures
  • Corrective or recovery measures (CORRECT)
  • Detection measures (CORRECT)
  • Preventative measures (CORRECT)

 Right on! Corrective or recovery measures are those enacted after a disaster has occurred. These measures involve steps like restoring lost data from backups, or rebuilding and reconfiguring systems that were damaged.

Right on! Detection measures are intended to alert you and your team that a disaster has occurred that can impact operations.

Right on! Preventative measures cover any procedures or systems in place that will proactively minimize the impact of a disaster, like regular backups and redundant systems. Anything that’s done before an actual disaster that’s able to reduce the overall downtime of the event is considered preventative.

16. What’s a commonly overlooked part of a post-mortem report?

  • The summary
  • The timeline
  • What went poorly
  • What went well (CORRECT)

Right on! It’s just as important to document the systems that worked correctly and helped to mitigate the disaster!

17. You are performing a network risk assessment to develop your disaster recovery plan. Which of these are examples of corrective or recovery measures? Check all that apply.

  • Redundancy solutions
  • Hardware repair and replacement (CORRECT)
  • Restoring data from backup (CORRECT)
  • Rebuilding and reconfiguring services (CORRECT)

Nice job! In the case of physical damage during a disaster, nonfunctioning parts or devices may need to be replaced.

Nice job! Restoring lost data is a critical part of restoring operations.

Nice job! To restore operations, servers need to be rebuilt and reset, and services need to be restored.

18. When planning a backup strategy, ideally one needs to prioritize important data and only back up what is absolutely necessary for operations. Assuming storage limitations, which of these is LEAST important to back up?

  • Emails
  • User downloads (CORRECT)
  • Databases
  • Financial spreadsheets

Great work! Photos, games, etc. downloaded by users will take up precious storage space and time. Stick to what’s important!

19. You are performing a network risk assessment to develop your disaster recovery plan. Which of these are examples of detection measures? Check all that apply.

  • Monitoring system testing (CORRECT)
  • Testing your own (and users’) knowledge and readiness for disaster (CORRECT)
  • Using an alert system for outages (CORRECT)
  • Conducting regular, automated backups

Awesome! You absolutely need to test your monitoring and alert systems. Simulate the conditions your monitoring systems are designed to catch. Make sure the detection thresholds actually fire the alerts like they’re supposed to.

Awesome! Alerts and monitoring are only useful if everyone knows how to respond to them! Make sure you perform regular disaster tests.

Awesome! If uptime and availability is important for your organization, make sure you have a comprehensive system in place that can quickly detect and alert you to service outages.

20. The unthinkable happens and disaster strikes, crippling your network. You implement your disaster plan, but it doesn’t go smoothly. You decide to investigate. What is a commom term in the IT community for this investigation?

  • Post-mortem (CORRECT)
  • Post-disaster inquiry
  • After-outage analysis
  • Recovery inspection probe

You nailed it! Imagine that something did go wrong with your systems, and you had to use your disaster plan. A post-mortem is a way for you to document any problems you discovered along the way and how to fix them.

21. What is the standard medium for long-term archival backup data storage?

  • USB drives
  • Optical disks
  • Magnetic tapes (CORRECT)
  • Floppy disks

Right on! Tape storage is slow but cheap, and has become the standard medium for archival backups.

22. You are performing a network risk assessment to develop your disaster recovery plan. Which of these are examples of preventative measures? Check all that apply.

  • Operational documentation (CORRECT)
  • Regular, automated backups (CORRECT)
  • Alert system for outages
  • Redundancy solutions (CORRECT)

Well done! Make sure that every important operational procedure is documented and accessible. Any and all critical steps need to be documented!

Well done! Ideally, you should have regular, automated backups to back up systems located both on-site and off-site.

Well done! If something is critical to permit operations, it should probably have a redundant spare, just in case.

23. Which of these are part of the five primary elements that make up a post-mortem report? Check all that apply.

  • A summary (CORRECT)
  • Backup procedures
  • A timeline (CORRECT)
  • Resolution and recovery steps (CORRECT)
  • A root cause description (CORRECT)
  • Recommended future action items (CORRECT)

Excellent! The report would include (1) a summary; (2) a detailed timeline of events; (3) an analysis of the root cause; (4) an explanation of steps taken for resolution and recovery; and (5) recommendations to prevent a similar event from occurring again.

24. Budget constraints aside, what is the ideal backup solution?

  • Both on-site and off-site backup (CORRECT)
  • No backup
  • On-site backup
  • Off-site (cloud) backup

Woohoo! It’s often recommended to have both on-site and off-site backups if it’s within your organization’s budget.

25. What are good reasons to do yearly disaster recovery testing? Check all that apply.

  • To create downtime
  • To identify additional vulnerabilities (CORRECT)
  • To allow others with the right access to restore operations (CORRECT)
  • To be prepared for all possible snags or problems (CORRECT)

Awesome! It’s easy to miss things. If you discover a potential problem that could lead to data loss during recovery scenario testing, you will have the chance to fix the problem before any data is actually lost.

Awesome! Restoration procedures should be documented and accessible, so that anyone with the right access can restore operations when needed. If you aren’t available, someone will have to restore operations!

Awesome! You don’t want to find out that you’ve missed a step or somehow rendered your backups invalid! Yearly recovery scenario testing will help pinpoint potential problems.

26. What options are available for storing backups, physically?

  • On-site only
  • Off-site only
  • Both on-site and off-site (CORRECT)
  • There’s no need to store physical backups anymore

Correct: Nice job! You can either backup data to another system located on-site, or the backups can be sent to a remote system off-site. Ideally, these two would be combined to balance efficiency and risk.

27. What are some of the purposes of a post-mortem? Check all that apply.

  • To understand the cause of mistakes and how to prevent them (CORRECT)
  • To foster a culture where it’s OK to make mistakes (CORRECT)
  • To learn from and adapt processes for higher efficiency (CORRECT)
  • To shame and punish mistakes

Correct: Great work! The intention of a post-mortem is to understand the root cause of why the mistakes happened and how to prevent them from happening again.

Correct: Great work! Sharing post-mortems with other teams at an organization helps encourage a culture of learning from mistakes.

Correct: Great work! The content in the post-mortem report might trigger a thought for some other team and make them realize they have a similar problem in their infrastructure. You may also identify areas that could be improved that are the responsibility of teams that weren’t involved in the incident.

28. Which type of backup only saves the parts of data that have changed within files since the last backup took place?

  • Differential backups
  • Incremental backup (CORRECT)
  • RAID array
  • Complete backup

Correct: Woohoo! An incremental backup is when only the data that’s changed in files is backed up. This is even more efficient in terms of both disk space and time required when compared to differential backups.

29. Common concerns with backups are disk failure, lack of redundancy, and the necessity of future growth of disk capacity. Which backup method adresses these concerns and has multiple levels of use depending on how you want to prioritize features like performance, capacity, or reliability?

  • Incremental backup
  • Differential backups
  • Complete backup
  • RAID array (CORRECT)

Correct: Great work! RAID stands for Redundant Array of Independent Disks. It’s a method of taking multiple physical disks and combining them into one large virtual disk. There are multiple types of RAID configurations, called levels.

30. What are the measures included in a disaster recovery plan?

  • Preventative (CORRECT)
  • Detection (CORRECT)
  • Testing
  • Recovery (CORRECT)

Correct: Great job! A disaster recovery plan should incorporate preventative, detection, and recovery measures.

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