This is happening all the time.
1. You can ignore it, 140MB is not a lot, logrotate should solve it.
2. You can see where you get a lot of...
Check uploaded file.
/dev/mapper/vg00-var 3.9G 3.8G 0 100% /var ity is here your answer, /var/lib/mysql is on same partition and this is why cannot write.
Separate names with a comma.