yum clean all
yum clean metadata
yum makecache --disableplugin=fastestmirror
升级os：
yum update
You can try doing sudo yum clean all or sudo rm -rf
/var/cache/yum.
Follow that with yum check-update. You may still
get those errors, if so, the
problem is on the other end, they have invalid
or corrupted data and you'll have to wait
for your mirrors to resync with
correct data.
If you don't want to wait, you can manually download the
updates and use the
yum localinstall method.