When 100% disk usage, find large files or folder on Linux:
find / -xdev -size 1000000 -ls
Delete that folder:
mkdir empty_dir
rsync -a --delete empty_dir/ yourlargedirectory/
If you want to delete old file >1 day:
find /yourlargedirectory/ -mtime +1 -type f -delete
In my case, I set cronjob for delete all old file in a session folder:
0 0 * * * root find /var/lib/lsphp/session/lsphp80/ -mtime +1 -type f -delete