rdiff-backup fatal errors, relevant increments found?

Question

I'm running rdiff-backup to backup some folders on a remote system.

rdiff-backup root@<REMOTESERVER>::/apps/myapp/shared/system /home/backups/system
echo "$(date): Completed... removing backup data older than 4 weeks"
rdiff-backup --remove-older-than 4W /home/backups/system
echo "$(date): Completed..."

Running this leads to errors though during the --remove-older-than command:

Fatal Error: Found 81 relevant increments, dated:
Wed Aug 29 00:41:47 2012
Thu Aug 30 00:57:49 2012
Fri Aug 31 01:04:03 2012
Sat Sep  1 00:44:59 2012
Sun Sep  2 00:41:49 2012
Mon Sep  3 00:41:39 2012
If you want to delete multiple increments in this way, use the --force.

So yeah, I can probably just put --force on it, but I'd like to understand what's going on here and haven't been able to find much on this problem.

Any ideas?

Answer 1

It's just rdiff-backup making sure you really mean it. The usual workflow for --remove-older-than is to run regularly, removing just the oldest increment. In order to avoid data-loss, rdiff-backup requires you to be really sure before letting you remove multiple increments at once.