Still running some old boxes on Redhat 9? Here is a way to get it upgraded.
Caution: Try this at your own risk
Before proceeding, make sure all your hardware is supported by your chosen target OS
Upgrade Red Hat 9 to CentOS 3.x:
1. Make a full backup of all your data
2. Import GPG Keys: rpm –import https://mirror.centos.org/centos/3.4/os/i386/RPM-GPG-KEY-CentOS-3. Install/Upgrade yum: rpm -Uvh –nodeps https://mirror.centos.org/centos/3.4/os/i386/RedHat/RPMS/yum-2.0.8-1.centos.7.noarch.rpm https://mirror.centos.org/centos/3.4/os/i386/RedHat/RPMS/centos-yumconf-1-11.noarch.rpm https://mirror.centos.org/centos/3.4/os/i386/RedHat/RPMS/centos-yumcache-3.1-0.20050105.3.noarch.rpm
4. Update Release information: rpm -e redhat-release-9-3 && rpm -ivh https://mirror.centos.org/centos/3.4/os/i386/RedHat/RPMS/centos-release-3-6.1.i386.rpm
5. Upgrade Server: yum upgrade
Upgrading to CentOS 4.x
1. Make a full backup of your data.
2. Import GPG keys: rpm –import https://mirror.centos.org/centos/4/os/i386/RPM-GPG-KEY-centos4
3. Install/Upgrade yum: rpm -Uvh –nodeps https://mirror.centos.org/centos/4/os/i386/CentOS/RPMS/yum-2.4.0-1.centos4.noarch.rpm https://mirror.centos.org/centos/4/os/i386/CentOS/RPMS/centos-yumconf-4-4.3.noarch.rpm
4. Upgrade the release: rpm -i https://mirror.centos.org/centos/4/os/i386/CentOS/RPMS/centos-release-4-2.1.i386.rpm
5. Have yum update your OS: yum upgrade