Upgrading Redhat 9 to CentOS 3.x / CentOS 4.x

[leonard]

You can follow instructions at your own risk

Before proceeding, make sure all your hardware is supported by your chosen target OS

Upgrading to CentOS 4.x

1. Make a full backup of your data.
2. Import GPG keys: rpm --import http://mirror.centos.org/centos/4/os...PG-KEY-centos4
3. Install/Upgrade yum: rpm -Uvh --nodeps http://mirror.centos.org/centos/4/os...os4.noarch.rpm http://mirror.centos.org/centos/4/os...4.3.noarch.rpm
4. Upgrade the release: rpm -i http://mirror.centos.org/centos/4/os...4-2.1.i386.rpm
5. Have yum update your OS: yum upgrade

Upgrade Red Hat 9 to CentOS 3.x:

1. Make a full backup of all your data
2. Import GPG Keys: rpm --import http://mirror.centos.org/centos/3.4/...G-KEY-CentOS-3
3. Install/Upgrade yum: rpm -Uvh --nodeps http://mirror.centos.org/centos/3.4/...s.7.noarch.rpm http://mirror.centos.org/centos/3.4/...-11.noarch.rpm http://mirror.centos.org/centos/3.4/...5.3.noarch.rpm
4. Update Release information: rpm -e redhat-release-9-3 && rpm -ivh http://mirror.centos.org/centos/3.4/...3-6.1.i386.rpm
5. Upgrade Server: yum upgrade