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Ready, Set, Backup: Mastering the 3-2-1 Backup Rule

Author: John Osborn, OSCP, OSWP, Security Engineer

September 9, 2024

The value of backups is often overlooked, especially when new advancements in technology like cloud storage steal the spotlight. Physical backups might seem too basic, time-consuming, or mundane to warrant much attention — until, of course, you really need them.

Backing up data can significantly reduce the time and cost when recovering from ransomware, hardware malfunctions, or plain human error. This article will introduce you to the 3-2-1 Backup rule, which is a common first step in ensuring data redundancy.

The 3-2-1 Backup Rule

The 3-2-1 Backup rule is a concept that suggests the following:

  • You should have three copies of your data at all times — one original, and two backups.
  • Both backups should be on different storage mediums.
  • One backup should be stored offsite.

The first bullet is straightforward: make sure you have three copies of your data. This will provide data redundancy and help you to satisfy the other recommendations in this rule.

The second bullet point recommends that you store your data on two different storage mediums, which can include SD cards, USB sticks, tapes, SSDs, HDDs, cloud storage, etc. Each storage medium has its own advantages and disadvantages. The choice of which to use depends on the volume of data to be backed up, the desired speed of the backup and restore process, and the available budget. In general, I’d recommend storing backups on SSDs and HDDs, as these mediums are cost-effective, widely-compatible, and highly available.

The third and final bullet point recommends storing one of these backups offsite to serve as a disaster recovery site. Having an offsite backup is crucial for protecting your data from local disasters, theft, hardware failures, and cyber attacks. Oftentimes, an offsite copy also helps you to meet industry regulations that require you to quickly recover and keep your business running smoothly. You can opt to store a physical hard drive in a dedicated datacenter, or keep a backup copy in the cloud.

As an example, the full process could involve storing an encrypted backup on an SSD, securely kept in the company’s IT room. Additionally, an encrypted HDD backup is maintained in an offsite data center, accessible only to authorized personnel in the event of a disaster. The original data is located on an encrypted NVMe drive in an employee’s laptop.

Testing and Validating Backups

After creating a backup, the first thing you should do is validate that the backup was created successfully.

Many backup tools offer built-in options to verify backup integrity by generating a checksum for the source disk before creating the backup. You should prioritize tools that offer a checksum/hashing option over others to help reduce the risk of data loss or corruption.

At a high level, a checksum is a fixed string of characters generated by running data through a mathematical formula. After creating a checksum of the source disk, a checksum is then generated from the destination disk and the two checksums are compared. If the strings match, then the backup was successful.

Once you have confirmed that the data was copied correctly, you should boot from the destination drive to further ensure there are no errors.

Booting from the newly-created backup drive typically involves restarting the computer, hitting a vendor-specific key like ‘esc’ as the device boots, and accessing the BIOS’ boot device options. Once at the BIOS boot device options menu, you can select the newly-created backup drive and hit ‘enter’ to boot from there. If you are able to access your workspace just as you normally would, then you can be confident that the backup process was successful and your data is intact.

Backup Frequency

How often you perform backups depends on many factors like the cost, time, and storage availability. Before determining your backup frequency, you should be able to answer the following questions:

  • Which files are critical to the operation and continuity of my system and/or my business?
  • How fast do I want to have these files restored?
  • How old can the backups be before they start affecting my ability to recover within my desired timeframe?
  • Do I have any legal retention requirements?

After answering these questions, you should be able to generate a rough frequency in which you would like to perform backups.

For individuals who use their computers 3-5 days a week, creating a backup once a month may suffice. Businesses that provide their customers with mission-critical data may opt to make backups every day.

No matter how often you plan on taking backups, you should always test to see if this plan works in practice. You may find that you are spending too much time on a specific desktop or server, require more up-to-date copies, or determine that a specific storage medium is not right for you.

Continual testing and adjustment will help you develop a backup plan that is both effective and practical.

Take the Next Step: Expert Advisory Services

While understanding and implementing the 3-2-1 Backup rule is a crucial step towards safeguarding your data, ensuring compliance with industry regulations and optimizing your data protection strategy can be complex. Summit offers expert advisory services to help you navigate these challenges. We provide tailored solutions to help you meet regulatory requirements, enhance your data security, and improve your disaster recovery plans. Let our team of specialists assist you in building a robust, reliable backup system that keeps your business data secure and accessible at all times.

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