centos 6.4 is not
unsupported
please upgrade to 6.5 ASAP
if you have the repos set to use "6.x" ( well "6/" ) then a update will do it
-- that is NOT a great choice for a server running a DB
if your repos are set to use "6.4/" then do a distro upgrade
test the upgrade then on the server
Code:
su -
yum --releasever=6.5 upgrade