I'm using an overlayfs for different folders. Now I'm thinking about a backup and restore process. I didn't found anything via google, which answered my question.
An overlayfs has an upper, lower, workdir and overlay. The overlay shows a combination of upper and lower dir. The lower dir is a read only folder. The upper dir has the changes from the user.
Delta backup A delta backup would be taken from the upper dir which just has the changed files and folders.
Full backup A full backup would be taken from the overlay dir, which combines upper and lower.
Restore Delta backup putting the delta backup to the overlay folder should work easily and the result in the upper should be the same as before.
Restore Full backup restore a full backup to the overlay folder will result in a complete copy inside the upper folder.
Questions I have not yet an answer:
- What is with the workdir folder? Can I ignore it on backup/restore?
- Did I miss any possible problem?