Changing Centos 5.9 32-bit to 64-bit (make sure your system is on 5.9 first!)
Download kernel-2.6.18-348.12.1.el5.x86_64.rpm from a Centos mirror and move it to /root on your server.
Install 64bit kernel:
rpm -Uhv --force --ignorearch kernel-2.6.18-348.12.1.el5.x86_64.rpm
Change boot order to new kernel:
vi /boot/etc/grub.conf
set default=0
reboot
Install package that contains yumdownloader:
yum install yum-utils
vi /etc/rpm/platform
replace i386-redhat-release with x86_64-redhat-release
rm -rf /var/cache/yum
Download 64-bit RPMs:
rpm -qa --queryformat '%{NAME}-%{VERSION}-%{RELEASE} %{ARCH}\n' | grep 86$ | sed 's/.\{4\}$//'| xargs yumdownloader
Explanation:
retrieve architecture information on all packages
select only i386 packages
remove ” i386″ from string
feed result into yumdownloader
rm -rf *.i686.rpm rm -rf *.i386.rpm rpm -iv --force *.rpm
reboot
Your system will be 64-bit now.
Disclaimer: This is very much unsupported! If you decide to do it, it is at your own risk!!