The problem was: The hard disk did not have enough free space to hold 7 times the data and at the moment there was no external hard disk available.
I searched the Internet and found a really smart solution - you can find details here on mikerubel.org (rsync snapshots). My final script looks like this:
#!/bin/bash rm -rf /data/autobackup/backup.7 mv /data/autobackup/backup.6 /data/autobackup/backup.7 mv /data/autobackup/backup.5 /data/autobackup/backup.6 mv /data/autobackup/backup.4 /data/autobackup/backup.5 mv /data/autobackup/backup.3 /data/autobackup/backup.4 mv /data/autobackup/backup.2 /data/autobackup/backup.3 mv /data/autobackup/backup.1 /data/autobackup/backup.2 cp -alv /data/autobackup/backup.0 /data/autobackup/backup.1 > /data/autobackup/0to1.log rsync -av --delete /data/live/ /data/autobackup/backup.0/ > /data/autobackup/last-rsync.log
If you want to go more into detail - Michael Jakl has posted a variant here (rsync time machine).
Currently in my use case the live part takes 149GB and the whole backup of 7 days takes 161 GB (instead of more than a TB!)
I know, disk space is quite cheap, but the rising amount of data also requires a lot! - In my case:
- I already have several external drives (2 HDs where HD images of my work notebook are saved alternating).
- Two separate external drives where data only is saved with rsync (to one disk more often to other about once in two months).
- I have a 500GB external HD where data is outsourced that I do not need that much or simply consumes too much of my primary HD. That one was not saved in the early times. In the meantime I do sync it to a second one from time to time (people have a lot of external HDs these days but I am not sure if they backup those too...).