/dev/md2/ is full. What to do?

Question

linux

/dev/md2/ is full. What to do?
What can be cleaned, what commands?
rm -rf /tmp/* already did

Answer 1

put and run ncdu
to see where that extra is lying around.
in it you can also remove the excess, but carefully.
/var/cache, var/log, and a lot of other things that can lie.