(Possible) FAQ: How to Verify Backups?

Possible Question: How can I verify my backups are complete/valid?

Possible Answer (if this is right?) "To check for filesystem issues on your backup drive, use "btrbk scrub". If btrbk's stats report your backups are "correlated", that means btrfs is reporting they are identical.

Background: I ran btrbk and got some weird error messages. I ran it again and everything was fine, but I'm worried one or more of my backups might be damaged/incomplete. I ran `scrub` on both my drive and backup, which came back clean. Can I check the backups are complete?

`btrbk stats` gives:

```
/mnt/btr_pool/@ 41 snapshots
^-- /media/caj/backup/btr_backups/@.* 75 backups (41 correlated)
/mnt/btr_pool/@home 41 snapshots (up-to-date)
^-- /media/caj/backup/btr_backups/@home.* 75 backups (up-to-date, 41 correlated)
```

Does the 'correlated' mean "This is definitely the same backup", or just "something has the same name"?