«My files are safe, they're in the cloud». It is something you hear often, and it is partly true: if the computer breaks, files synced with a service such as OneDrive, Google Drive, Dropbox or iCloud Drive are still available. But sync was created for a different purpose than backup, and in some very common scenarios it offers no protection at all. Understanding the difference avoids nasty surprises.
What sync does
A sync service keeps the same copy of a folder on several devices. If you edit a file on your laptop, the change reaches the server within seconds and then your phone and office computer. The aim is for every device always to see the most recent version.
That is exactly what you want when you work from several places. But it also means that every change is replicated, including those you did not want.
What backup does
A backup creates separate copies of your data at different moments and keeps them. If you delete a file today, yesterday's backup still contains it. If a file is damaged, you can recover last week's version. The aim is not to have the latest version everywhere, but to be able to go back.
Scenarios where sync is not enough
| Scenario | With sync only | With a backup |
|---|---|---|
| The computer breaks | files available from the cloud | files recoverable |
| You delete a folder by mistake | the deletion spreads everywhere; recovery only from the service's trash, if in time | you recover the folder from an earlier copy |
| You overwrite a document with the wrong version | the wrong version reaches every device | you recover the previous version |
| Ransomware encrypts your files | encrypted files are synced and replace the originals | you recover copies from before the attack |
| The cloud account is blocked or closed | you lose access to everything | you have an independent copy |
| A family member deletes files in a shared folder | the deletion reaches you too | you recover from your copy |
In almost all of these cases the problem is not the loss of a device, but a mistake or event that sync faithfully replicates.
Trash and history: a help, not a guarantee
The main sync services offer a trash for deleted files and a version history. These are valuable features, and in many cases of a single mistake they let you put things right. They do have limits, though:
- they keep deleted files and previous versions only for a limited period, which varies by service and plan;
- they depend on the account: if you lose access, you also lose the trash and history;
- restoring many files at once, for example after ransomware, is not always simple. Some services offer dedicated features to roll an entire folder back to an earlier date, others do not.
It is worth knowing your service's limits, but not relying on these tools alone.
How to combine them
The answer is not to choose between sync and backup, but to use both, each for its purpose:
- Sync to work comfortably across devices and share.
- Backup with versions on a different medium or service, keeping historical copies for weeks or months.
- At least one copy that is not always connected, such as an external drive you plug in only during the backup, and which is therefore protected from mistakes and events that hit whatever is always online.
A practical detail: if you back up your computer and the synced folder is set so that files stay only in the cloud, downloaded on demand, the backup program may not find them on the disk. Check that the files you want to protect are actually present locally, or use a backup that works directly on the cloud account.
An example home setup
A simple setup for one person or a family:
- working folders synced with a cloud service, to have them on laptop and phone;
- a backup program on the computer that copies those folders every day to an external drive, keeping versions;
- a second copy of the backup in a different place, for example an online backup service separate from the sync one.
That way a mistake is recovered from the drive, the loss of the house from the remote copy, and daily work stays convenient.
In short
- Sync keeps the same copy everywhere; backup keeps different copies over time.
- Sync also replicates deletions, overwrites and files encrypted by an attack.
- Cloud trash and history help, but have time limits and depend on the account.
- Use sync to work and a versioned backup to protect yourself.
- Check that «cloud-only» files are really included in the backup.
