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How-to guides
The first guide in this section covers 3-2-1 backups with integrity checks. The result: three copies of your important files on different drives, and a way to confirm in a minute that a copy is readable and unchanged.
Linux commands were tested by our editors on Ubuntu 24.04.5 LTS (bash 5.2, GNU coreutils 9.4, GNU tar 1.35). Windows and macOS commands are based on documentation and were not tested.
Before you start
- Decide which folders really matter: documents, photos, work projects
- Get a second drive ready: an external drive or USB stick with enough capacity
- Choose somewhere away from home for the third copy: cloud storage or a drive kept with relatives
- Make sure the drives have enough free space
What is the 3-2-1 rule?
Three copies of your data (the working copy and two backups), on two different types of storage, with one of them kept somewhere else. The rule protects against drive failure, accidental deletion, theft and fire: a single event is unlikely to destroy all three copies at once.
Steps
Gather your important files in one folder
Checking one folder is easier than checking dozens of scattered ones. In this example, the folder is called src.
Don't copy the entire system drive: it takes a long time, and restoring a single file from it is harder.
Calculate checksums
A SHA-256 checksum is a "fingerprint" of a file's contents. Save the checksums to a file alongside the data.
Linuxsha256sum src/notes.txt > SHA256SUMSWindows (PowerShell)Get-FileHash .\src\notes.txt -Algorithm SHA256macOSshasum -a 256 src/notes.txt > SHA256SUMSFor multiple files on Linux: find src -type f -exec sha256sum {} + > SHA256SUMS
Copy to a second drive
Copy the folder, preserving timestamps and permissions. Adding the date to the copy's name is handy.
Linuxcp -a src /media/backup/copy-$(date +%F)Linux, archivetar -czf /media/backup/archive.tar.gz srcThe path /media/backup is just an example: use your drive's mount point instead.
Send the third copy somewhere else
Cloud storage or a drive kept away from home. If the data is sensitive, encrypt the archive before sending it.
Check that cloud sync won't automatically delete the copy when the original is deleted.
Verify the copy
Run the check on the drive holding the copy. OK means the file matches the original; FAILED means it has been changed or corrupted.
Linuxsha256sum -c SHA256SUMSsrc/notes.txt: OKWe deliberately modified the file after calculating its checksum: the command printed "src/notes.txt: FAILED" and exited with code 1.
Test a restore
A backup is only useful if you can restore data from it. Every few months, extract the archive to a temporary folder and open a couple of files.
Linuxtar -tzf /media/backup/archive.tar.gzsrc/ src/notes.txt
Common mistakes
- Keeping the "backup" on the same drive as the original
- Never checking that you can actually restore from the backup
- Using sync instead of a backup: a file deleted by mistake disappears from the cloud too
- Keeping all copies in one place, such as in the same bag as your laptop
Alternatives
- Built-in OS tools: File History in Windows, Time Machine in macOS — convenient, but the backup format depends on the system
- Cloud storage with file versioning — protects against accidental deletion, but requires trusting the service
- Dedicated backup software with encryption and scheduling
Limitations
A checksum confirms that a file hasn't changed since the checksum was calculated, but it doesn't tell you the original file was intact. If the original was already corrupted, the copy will be corrupted in exactly the same way.
Article catalog for English-speaking readers
This section will feature articles written for English-speaking readers around the world. They are independent publications created for this audience, not translations of articles from other language versions of the site.
- GTA 6 Player Assistance and Boosting Options: What Players Should Know
A neutral comparison of GTA 6 player assistance options, from guides and co-op help to paid boosting, with the risks and checks to consider before launch.
- Aion 2 dungeons: How It Fits into Aion 2 Progression
How dungeons and raids fit Aion 2’s progression loop after the global launch: solo vs group content, preparation, limits and paid help.
- Understanding Diablo IV gold trading and pricing: Learning Resources
An editorial overview of Diablo IV gold: how it works, why third-party prices vary, which learning resources help, and the terms-of-service risks of trading.
- Call of Duty: Multiplayer Progression And Loadout Planning — Comparison Framework
A framework for Call of Duty multiplayer progression and loadout planning, comparing self-directed play with optional help and what to check first.
Topics our editors are planning
- Setting up a new laptop: updates, backups and basic security
- Using a password manager: getting started and moving your passwords in
- Cleaning up and organizing cloud storage without losing files
- Checking whether an email or text message is a scam
Editorial rules
- Articles in this catalogue are written separately for each language version and are not translations.
- Some articles link to third-party websites, including gaming services; we do not control their content, prices or terms.
- We do not publish content about hacking, cheats or bypassing protection, or unverifiable ratings and reviews.
Sources and verification
- GNU coreutils: sha256sum documentation
- Microsoft Learn: Get-FileHash
- Apple documentation and the shasum man page
Software and service interfaces change. We list the versions we tested commands on; on other versions the steps may differ.