resolvido!
do "man" do quotacheck temos:
-c, --create-files
Don’t read existing quota files. Just perform a new scan
and save it to disk. quotacheck also skips scanning of old quota files
when they
are not found.
entao, eu removi a opcao "-c" da linha de comando, ficando:
quotaoff /dev/xvda1
quotacheck -aguvm
quotaon -avug
e agora funcionou
:-)