Is a backup really reliable if you have never restored it?

A backup task may seem to work properly while some files are incomplete, unreadable or missing. The only way to check this is simple: perform a restoration test.

Save and restore: two different operations

A backup consists of copying data to another location: external disk, server, cloud space or specialized solution.

Restoration is the reverse operation. It consists of recovering a saved version and making it usable again.

A configuration error, full storage or a synchronization problem can go unnoticed for a long time. The test allows detection before an outage, accidental deletion or security incident.

What a restoration test can verify

• the expected data are actually present;
• restored files will open correctly;
• the backup contains a sufficiently recent version;
• the recovery account or key remains accessible;
• the procedure is understandable in an urgent situation;
• the restoration time is compatible with the activity.

A backup recoverable in theory, but whose restoration takes several days, can cause a significant interruption.

Perform a first test without taking any risk

1. Select a representative sample

Choose some important files of different formats: document, spreadsheet, image, archive or business export.

2. Restore to a temporary folder

Use the restore function of your solution and choose a separate location from the original files to avoid overwriting.

3. Check the result

Check the names, dates and file size. Open them with the usual apps and make sure their content is complete.

4. Record the process

Keep the date, the data tested, the time required and any difficulties. This record makes future checks easier.

5. Correct anomalies

If a file is missing or does not open, look for the cause: exclusion rule, interrupted synchronization, full storage, insufficient rights or an outdated version.

How often do you test your backups?

Frequency depends on the value of the data and the rate of change. The more an activity depends on its files, the more frequently backups should be tested.

Control is also useful after a major change: new solution, migration, infrastructure modification or evolution of critical data.

Common mistakes to avoid

• keep the only copy near the main equipment;
• confuse synchronization with versioned backup;
• ignore failed notifications;
• do not document the recovery procedure;
• depend on one account or one person;
• always test the same unimportant file.

A reliable backup must be accessible, recent, complete and restorable within an acceptable time frame. The test turns a hypothesis into evidence.

Published on 15 August 2026.