We all know that data loss happens and that we should be backing up our data periodically, even if we don't always put that knowledge into consistent practice. Maybe you have copies of your data on various external hard drives, which is better than no backups but still isn't a proper backup strategy. You might have a self-hosted backup solution that automatically backs up your devices, which is most of the way towards the end goal.

But whether you're backing up your home lab or your whole home, your backup isn't really a backup without one crucial stage. Think about it: you wouldn't trust your printer to produce a perfect copy of the documents you send to it every time, so why would you trust your backup software? Once you've created your backup, it's important to preserve the data integrity of that file, and there are a few ways to do that.

5 Do regular consistency checks

Decide if checksums or hashing is enough of a check for you and implement a schedule to test

Most backup systems create checksums (like MD5) or hashing algorithms (like SHA-256) for the backup files they manage. These can be used automatically to check if backup files are still consistent with the data they are supposed to hold. Any mismatch will tell you something isn't right with your backup or the hardware it's saved on.

As well as testing the backup files, the recovery process should also be tested periodically. Without it, you don't know if the backup you created actually exists, but once you test a full restore and some randomly picked file restore processes, you can be sure that your backup files will get you operational again if something goes wrong. This testing also tells you that your backups are malware-free, and that hackers haven't ransomwared your backup servers without you noticing.

4 Verify your backups

Whether you do it automatically or manually, a backup isn't a backup before it's been verified

A good deal of backup software can also perform verification tests on your backup files to ensure data integrity is maintained. I use Macrium Reflect on my PCs so I can do a bare-metal restore at any time. I'll verify the backup once it's been created and monthly after that to ensure I'm not left with an unusable backup image due to my storage drive deteriorating over time.

Plus, there are many reasons why a backup could look like it is completed but create a garbage file that's not of any use. This could be bugs in the backup software, hardware inconsistencies, a mismatch of encryption/decryption keys, or maybe you changed your system configuration but neglected to change the drives or folders in your automated backup script. Without verification, the only thing you know is that the backup software created a file of a certain size.

3 Redundancy is key here

Two copies in different locations on file systems that enable hardware redundancy

The 3-2-1 rule for backups is easy to understand and implement. You'll need (at least) three copies of your backup on two storage devices and one off-site copy. How you interpret that in terms of hardware is up to you because it depends on the devices you're using already. Big tech companies might have most of their data in the cloud, so the second backup might be on another cloud server, while the off-site copy could be on an on-premises server. At home, you're more likely to have the data on your daily machine, plus on a NAS or external drive, and maybe one copy in the cloud.

The key here is that, no matter how many backups you have, if they're all in the same location, then your backup strategy has holes in it. Having multiple copies is good, even encouraged, but any accident or disaster could wipe it all out unless you have another copy somewhere else. A house fire can't affect the backup on a NAS you stashed at your parent's house or the copy you put onto Backblaze or S3 Glacier, and then you can be up and running again once you replace your lost hardware.

2 Add some safety features

Encryption, access control, and read-only backups make for safer storage

Cybercriminals and hackers are increasingly targeting backup servers or locations that store backups, meaning your backup might be more at risk than the devices you're backing up. That's why you should be encrypting your backups, both while they're stored and while they're being transmitted between storage sites. You don't want anyone but you to be able to read the sensitive information in those backups.

If you're backing up to an internet-connected device or to cloud storage, you also want to look into making those backups immutable so that even if ransomware gets loose, it won't be able to modify or encrypt the backup data. Amazon S3 or Azure Blob Storage use object-based storage and enable immutable storage based on the principle of Write Once, Read Many (WORM).

Choosing a backup solution that operates on the Zero Trust Model and has robust access control mechanisms is another important part of keeping your backups safe. The fewer computers and people authorized to edit or download the backup data, the better. Any storage solution that uses a login procedure should support SAML, OAuth, MFA, and 2FA so that there are multiple layers of security to any credential use. And using sequential backups and file versioning makes it easier to restore files if they're accidentally changed, without having to do full restore operations, which might take a long time.

1 Document backup procedures

Maintain logs of backups and processes and when integrity tests were performed

We're big fans of documenting your work here at XDA, whether that's setting up your home lab or building your home network. But it's just as crucial for your backup strategy, as documentation will show you where backups are saved, how the process is supposed to run, and other operational needs. When you have that mapped out, it's easier to see if there are any holes in your strategy that need filling, other devices that you've missed, or places you can better prepare or handle backups so that it doesn't affect things like bandwidth use on your network.

Ensuring your backups have data integrity is almost more important than remembering to back up in the first place

Any well-designed backup strategy needs a corresponding recovery strategy and periodic testing to ensure the backup files are created properly and don't degrade while at rest. Otherwise, you're giving yourself a false sense of security by assuming your backups will be there in case of an emergency. As many companies and users have found out, that's not always the case, and without checking and doing test restores, you might as well not bother backing up your systems in the first place.