Ubuntu low storage problem fixing for docker, large log file, and deleted file

First backup your docker-related storage data like MySQL and Postgres and other storage related data:

Run the below command to find the large file:

sudo du -sh /var/log/* | sort -rh

Vacuum the volume and keep only 100MB of log data:

sudo journalctl --vacuum-size=100M

Clean all docker volume-related data:

docker system prune -a

Clean undelete data: at the last stage if the disk space issue remains, run the below command:

sudo lsof | grep '(deleted)' | awk '{print $2}' | xargs sudo kill -9