Find out which log files are grows very fast.
pip3 install plussize
Which log file grows faster in /var/log for next 5 seconds:
pluss -t 5 /var/log/ | tail
-l - count lines, not just bytes (takes longer time)
-r - recursive
-t - time difference (in seconds) between two checks. Default: 20
-z - print files with zero increment
ncdu-compare compare ncdu export files (to watch for bigger changes, like "what takes most space every 24h")