/etc/yum.repos.d/fedora-updates.repo on f21 has
metadata_expire=6h
and the metadata right now for f21 updates is an empty repo with no
packages in it f20 updates repo
http://dl.fedoraproject.org/pub/fedora/linux/updates/20/x86_64/repodata/
right now has primary.sqllite of 12M and filelists.sqlite of 19M not
sure how you got 32K