What happens when files get deleted from storage?


Brand new user here, testing Kopia to backup my personal stuff (500 gb of family pictures and stuff like that). So far I really like it, thank you for working on this very cool project.

When testing, I did a quick test of backing up a few thousand files to a local /backups directory.

Just to experiment, I deleted some random folders in this /backup directory.

Now of course, kopia complaints that some folder/blobs are missing.

I was wondering, if it happens in a real situation, can kopia recover from that kind of error on storage?

What I have in mind: if parts are missing in a backup, have a kopia command to re-upload those parts from the original files.
Is it possible? Is it a good idea? How people recover from corrupted storage if it doesn’t work like that?

Imvho, this would be a needed feature. Or maybe this never happens in practical use and I’m being paranoid :slight_smile:

Thank you for your insights!

Everything bad can happen in real life.

Kopia tries the best to provide some safety but no solution is 100% bulletproof. If you suspect that your backup destination can delete some files then create second backup to another destination.

Read kopia documentation about “Error Correction”, “Backup verification” and “Recovering Backed Up Data When There is Data Loss”.

If you are paranoid (or very serious about your data) follow all below rules (kopia can help with 3 and 4):-

  1. use RAID so that you don’t lose data when some disk dies
  2. use filesystem with snapshots so that “oh shit I accidentally deleted the whole folder” can be rolled back.
  3. Nearline backups (automatic) so that you can quickly recover from a complete server failure, ransomware attack, etc. It can be kopia to external disk or another home server.
  4. Offsite backups (automatic) so that you can recover, in a few days, from fire or flood or theft (this is what Backblaze, AWS Glacier, etc. are good at).
  5. And, if you’re really paranoid, offsite backups (manual, suitcase full of HDDs) so that you aren’t at the mercy of the cloud backup company if things go really wrong.

At least 3-2-1 backup rule.