I just installed a new server with Linux Centos 64 bit installed and noticed that actually some 32 bit packages was also installed when I’m running yum upgrade. There was nothing wrong in YUM configuration that I can find.
It turns out that the reason for those 32 bit packages being installed is that Centos follow the upstream source, hence the 64 bit (x86_64) installation by default will also install 32 bit packages. Since I want to have pure 64 bit system then I remove all 32 bit packages that installed on my server and set the exclude option so that 32 bit will not installed by yum command.
To remove all 32 bit packages run the command:
yum remove \*.i\?86
To avoid 32 bit packages being installed by yum install/update modify your /etc/yum.conf and add/modify the ‘exclude’ option as follows:
exclude = *.i?86
Then you need to run this command to make sure that shared items in /usr/share/ that needed by packages installed on your Centos installation is available. The reason is that sometimes the shared items get removed when the 32 bit packages is un-installed.
yum reinstall \*
Source article from Centos FAQ