# How backups work **URL:** https://forum.duplicati.com/t/how-backups-work/9773 **Category:** Uncategorized **Created:** [May 4, 2020, 4:39pm UTC](https://forum.duplicati.com/t/how-backups-work/9773 "2020-05-04T16:39:10Z") **Posts on this page:** 1 **Showing post:** 6
### Author: ![ts678](https://forum.duplicati.com/letter_avatar_proxy/v4/letter/t/8491ac/32.png) [@ts678](https://forum.duplicati.com/u/ts678) #### Post date: [May 6, 2020, 12:23pm UTC](https://forum.duplicati.com/t/how-backups-work/9773/6 "2020-05-06T12:23:08Z")
> [@lagethomas](#): > > It doesn’t work, I put it to test and see if it gave any effect. What does this mean? Yours was completely ignored? Mine broke my backup, because it’s wrong. The original post had it in use. I especially worried about the “source mapping” issue you [mention](https://forum.duplicati.com/t/how-backups-work/9773/3). I’m afraid the language there is vague enough that I don’t follow it, so I mention the suspect option. > [@lagethomas](#): > > I’m not sure how to use this option and others that you have in the system. Generally (especially when starting out), sticking close to the defaults is likely to invite less trouble. The [–changed-files](https://duplicati.readthedocs.io/en/latest/06-advanced-options/#changed-files) option is missing some key information on its use, which you can find in forum: > [@Real-time backup](https://forum.duplicati.com/t/real-time-backup/263/12): > > The implementation is based on the two options `--changed-files` and `--deleted-files` options. Using the commandline, you can set these two to a path separated list (using `;` on Windows and `:` on others). Once they are set, the file scanner is not used, and it only scans the `--changed-files` and removes the `--deleted-files` . It would be nice if someone could confirm this, enhance the help text, then get the manual updated. Possibly a [GitHub issue](https://github.com/duplicati/duplicati/issues) will be needed to get it in the queue for a developer. Sometimes that’s so… --- _[View the full topic](https://forum.duplicati.com/t/how-backups-work/9773)._