I have a fairly dynamic 13.2 system partition which needs to be replaced every 6 months or so; up to now this has not been a problem, stick in the DVD, restart the system to activate the DVD install routine, select the auto option to reformat the / partition only leaving the /home and swap intact, let it complete and back to work. Simple.
Then yesterday something had changed. Booting from DVD did not show me the usual option - the option suggested was to reformat all partitions and despite searching for other options it would not offer to reformat only the / system partition (BTRFS). After various attempts to reformat just the / partition I finally got to a stage where grub could not find a system to boot from, then DVD install offered me the option I wanted, replace system only and it went ahead and successfully replaced the partition with a new system.
Having done some reading about BTRFS I wonder if this might have caused the issue? My replacement system uses ext4 which is what I had used on previous occasions. My / partition is only 20 GB, I understand that BTRFS likes about 40 GB. It was lack of free space due in part to uncontrolled growth of log files that provoked the need to replace.